Hello @Oliver-1xok, just to check, was PROTON_LOG=1 %command% -dx11 what you tried to use in the game's launch options to generate a log?

Of course not. :/

Thank you for the hint! Sorry, my mistake. The proton logs are generated without problems. I added them to the report and also recreated the output of the PS command.

(I also updated Steam Info again, because my Steam Client has been updated in the meantime.)

D3D11 GPU hangs should be fixed as of https://github.com/doitsujin/dxvk/commit/4aa6800e95b093f259123107190ca56dae24e3be.

Do note that the renderer seems to be quite buggy so there might be further issues.

can confirm with https://github.com/doitsujin/dxvk/commit/4aa6800e95b093f259123107190ca56dae24e3be
Rocket League runs without issues under D3D11, i played some rounds without any issues.

can confirm with doitsujin/dxvk@4aa6800
Rocket League runs without issues under D3D11, i played some rounds without any issues.

Just for clarity: You tested it with a self-compiled version of DXVK that contains https://github.com/doitsujin/dxvk/commit/4aa6800e95b093f259123107190ca56dae24e3be ?
And you also tested it with an Nvidia card?

(I haven't had time to test it yet.)

correct, but i didn't compile it myself :) Philip has his buildbot :)
https://git.froggi.es/doitsujin/dxvk/pipelines?scope=finished&page=1
I overwrote the 32bit and 64bit dll's in proton 5.0-2 (released some minutes ago) inside steam.
Yes i use Nvidia it is a GTX 1070.
Played again around 30 minutes without issues

correct, but i didn't compile it myself :) Philip has his buildbot :)

Ah, it's easier, of course. Thanks for the advice!

can confirm with doitsujin/dxvk@4aa6800
Rocket League runs without issues under D3D11, i played some rounds without any issues.

Can also confirm. I tested again with proton 5.0-2. With the release version of DXVK the game did not start. Then I used this build:

https://git.froggi.es/doitsujin/dxvk/pipelines/1068

I copied the libraries from "build/dxvk-release/x64" to "steamapps/common/Proton 5.0/dist/lib64/wine/dxvk".

Rocket League runs normally afterwards. It doesn't run as smooth as the D9 version due to the missing VSync in this experimental version. But this is another problem.

So I think Philip has fixed this problem.

Rocket League runs normally afterwards. It doesn't run as smooth as the D9 version due to the missing VSync in this experimental version

You can force vsync via dxvk.conf options, specifically dxgi.syncInterval = 1.

hm in proton were should this dxvk.conf file go? i created one in my steam folder, and in Steam at the run options i added DXVK_CONFIG_FILE=/home/mine/Games/Steam/dxvk.config but it seems to get ignored

The environment variable should work fine, best double-check whether both the path and content of the file are correct.

What is the default location for the dxvk.conf file?

What is the default location for the dxvk.conf file?

There is no default. Set the following launch option

DXVK_CONFIG_FILE=/your/dir/here/dxvk.conf %command%

Of course you have to replace /your/dir/here/ with the directory where your dxvk.conf is located.

You can download a commented dxvk.conf to your current directory with this command:
wget https://raw.githubusercontent.com/doitsujin/dxvk/master/dxvk.conf

You then simply adapt this conf to your needs. It works fine. Just tested it.

You can force vsync via dxvk.conf options, specifically dxgi.syncInterval = 1.

I did not know the VSync option yet. Great option. The game becomes very smooth again. Works better than the VSync implementation by the Nvidia driver, which almost always results in micro stutterers.

The only thing I notice with dxgi.syncInterval = 1 are regular yellow spikes for single frames in the frame time graph during gameplay. The max frame time doubles from 17 ms to most 34 ms. However, I do not notice any disturbing stuttering. I don't really notice anything. I just see it in the graph.

Without VSync my GTX 970 reaches 120 to 180 fps in the DX11 client of Rocket League. 120 fps constant in any case. (With all graphic settings at maximum.)

This just for feedback.

Though the DX9 version seems to start up and work. Rocket League DX11 version has stopped working again. The logs are identical to the ones posted originally in the issue (at least to my untrained eye).

steam-252950.log

The log is generated with latest mesa-aco from Valveaur repo, but even with regular mesa 20.x the dx11 version of the game was not working

Works for me with the -dx11 flag

GPU: GTX 1050 Ti
Driver/LLVM version: nvidia 435.21
Kernel version: 5.3.0-42
Proton version: 5.0-5

Don't forget to force the use of steam play because Psyonix is no longer supporting the game on linux

After further testing, It seems that the Rocket League DX11 version does indeed start, but it does so after stalling at the startup logo for a good while (full 2 minutes as per my stopwatch). In the meanwhile the menu music is playing in the background even though the game is still showing the Psyonix start up logo. After two minutes when it finally reaches the menu, the "Press any button" starts blinking rapidly as if catching up to the amount of blinks it missed due to the delay. After a while it too settles down into the normal rhythm.

Something strange is going on, I must admit.

For completion's sake, I am attaching another log, after entering the game and closing it.

steam-252950.log

EDIT: For some reason (probably an update at my end), the game is now starting up properly.

AMD user here, I'm getting stutters after a few games, growing worse and worse.
Restarting rocket league doesn't seem to have any effect, but restarting my pc does. This to me feels like some form of memory leak or something like that? Haven't tested if e.g. restarting steam works too, I'll try working out what the exact "refresh" trigger is in the following days (takes a few games (or X time?) for the stutters to get noticably bad).

I haven't experienced this issue with Monster Hunter World, the only other game I've really played on my new machine, so I'm guessing it has something to do with rocket league, but not very sure.

I'm not running anything else apart from discord as this is a fresh install of ubuntu 20.04
Proton: tried with both 5.0-6 and 5.6-GE-2
CPU: AMD Ryzen 7 3700X
GPU: AMD Radeon RX 5700

other system details here: https://gist.github.com/JoranDox/ccc321a93a5f7105f698a9eaccd29e59
protonlog: steam-252950.log

Appreciate the response @kisak-valve , will try to fix the mismatch: does seem like that's the issue in retrospect.

After latest recent game update, steam update, and proton update (so I ignore which update is the cause), the game or steam client is crashing when starting, both game and steam closes. This is the log.

I'm having this error when trying to launch the game

Hello @Zuchter, Binaries/Linux/RocketLeague was the name of the native linux binary. If you want to test the game with Proton, go to the per-game properties and enable Proton in the Steam Play section.

I will try what you said but I found something else, I went into the game files and there was nothing there. The Rocket League folder was literally 8KiB. Seems like steam doesn't even download the game

edit: Nevermind, after trying what you said it started downloading the full game now. Thank you

as @kisak-valve said, click settings icon of game, then properties

Then, check option For the use ... and select Proton

I am using a dual-monitor setup. When launching Rocket League, when set to borderless or fullscreen, it will now choose my secondary monitor instead of my main one. Before Proton 5.13, it shows on my main monitor (which is a high-refresh rate monitor) correctly. I assume this has something to do with it now being in an isolated container...

I would like to note that this does NOT happen with all games! For instance, the game Ascent fullscreens on my main monitor correctly, regardless of Proton version.

After updating to Ubuntu 20.04, I am not longer able to launch Rocket League using Proton 5.13-2. I've tried all other available Proton versions from the Steam Play menu, with same results.

When I launch the game, a black window appears with the title "Rocket League, DX11, Cooked", and after 10-15 seconds, a cursor appears and the menu music starts playing. Still with a black screen.

The only way I've managed to launch the game is with the PROTON_USE_WINE3D=1 flag, but this results in terrible performance (5 fps, so unplayable)

Attached is the proton log generated:
steam-252950.log

Any suggestions? Thank you in advance!

EDIT: SOLVED
Downgrading and using Proton 5.0-10 appears to solve the issue. Unclear why.
Let me know if someone wants to investigate further, I can upload additional logs.
Leaving original description for reference.

Any suggestions? Thank you in advance!

Still running fine on ArchLinux after Proton 5.13-2

After updating to Ubuntu 20.04

Get rid of it (like I did myself many years back), it's inferior.

Hello @nuno1212s, I'm not that familiar with AMD+nVidia systems like yours, but you might be seeing something similar to ValveSoftware/steam-runtime#312 and if that's the case, then it might be worthwhile to test temporarily disabling mesa/radv with something like sudo mv /usr/share/vulkan/icd.d/radeon_icd.x86_64.json /usr/share/vulkan/icd.d/radeon_icd.x86_64.json.disabled and see if that has an effect.

This fixed my issue. Does this config have effect on the whole system or just how proton runs games? If it's system wide, do you have any idea if it will get reverted if I change back to hybrid graphics?

I'm not sure how to debug this, but since recently the game doesn't react to controller input; Keyboard still works fine.
This is happening with proton-experimental

still broken with latest update, works when the game uses xbox buttons though (proton experimental)
when wired proton uses the Xbox controller scheme (vibration works!)
on Bluetooth proton uses the PlayStation controller scheme (vibration no work)
tried a different game and vibration dosen't work on bluetooth either
am using heroic games launcher if that makes a difference

After recent (a few weeks ago) voice chat update the game has the issue that you can't hear how other players talk unless you change audio device once per game:

• https://www.protondb.com/app/252950#PHT_KWuT65=

when they added the voice chat function, I sometimes lose the audio and have to switch input and output settings around to make it work again, temporarily. It can be finicky, and other times I have had no issues.

• https://www.protondb.com/app/252950#Es0bC0dEEb

In game Voice call -- Every new match that starts, all sound works except I cannot hear anyone in the voice call. At the start of each match, I have to change the voice call output device to either 'default' and 'The_Name_of_The_Device' (Only set it once for the match. If it is currently on default then change to the name and vice versa.)

• same for me

Guess it's Linux / Proton specific issue.

dualsense controller support is still broken, it's actually kinda sad that stock wine is better at gaming lmao (they patched it in wine 7.3)

Had a problem with the last couple of updates to Proton Experimental where nameplates weren't showing, or would be blank, or some would be the colour of the opposite team, which all make it very tricky to play.

With 7.0-3 it's working as expected.

Hello @ryliejamesthomas, please copy your system information from Steam (Steam -> Help -> System Information) and put it in a gist, then include a link to the gist in this issue report.

Sorry about that. Here's my system info: https://gist.github.com/ryliejamesthomas/109d136add6de5cb99e9cc140d4c51d9

@tatsujb

Symptoms

player Nameplates don't appear since the 12th of July 2022 as you can see neither my teamates nor myself have a nameplate and that makes players hard to see.

I did some digging and this was a dxvk regression and should already be fixed in experimental-bleeding-edge (and thus in the next experimental update). Please let me know if the next experimental release does not fix this, ty :)

Anyone else still unable to use Anti-Aliasing in game? Any workarounds found?

Anyone else still unable to use Anti-Aliasing in game? Any workarounds found?

I noticed this too, the anti-aliasing dosen't seem to do anything. I would probably make a issue on the dxvk github about it though.

Can you post a screenshot of what it looks like vs what it's supposed to look like on Windows?

Also seeing the https://github.com/ValveSoftware/Proton/issues/3521#issuecomment-1143119319 voice chat issues.

Regular audio works fine though. (Using pipewire)

It seems some XAudio2 device is exiting very early on:

[0011.06] Exit: XAudio2 Device shut down.

Below kinds of errors seem to show up for each match.

[0494.67] EOSVoice: Received full credentials from the server.
[0494.67] EOSVoice: Joining room 46190D3611EE65218B3F669003816124-0
[0494.68] PsyNet: PsyNetServiceProvider_X_1 ExecuteService Complete, Service=VoiceChat/MatchToken 
[0495.47] EOSVoice: SetPlayerMuteStatus for player [redacted] in room 46190D3611EE65218B3F669003816124-0 to False
[0495.49] Error: EOSSDK-LogAudioMixer: XAudio2 Error: Result -> 0x800401F0: UNKNOWN (line: 436)
[0495.49] DevOnline: EOSSDK-LogEOSRTC: RTCRoom [46190D3611EE65218B3F669003816124-0 bf1...37b] QueryOutputDevices failed 2147483647
[0495.49] DevOnline: EOSSDK-LogEOSRTC: RTCRoom [46190D3611EE65218B3F669003816124-0 bf1...37b] The specific output device id '{0.0.0.00000000}.{FD47D9CC-4218-4135-9CE2-0C195C87405B}' has not been found. The default device index '-1' will be used instead of it
[0495.49] Error: EOSSDK-LogAudioMixer: XAudio2 Error: Result -> 0x800401F0: UNKNOWN (line: 850)
[0495.49] Error: EOSSDK-LogEOSRTC: RTCRoom [46190D3611EE65218B3F669003816124-0 bf1...37b] unable to get output device information by index[-1]. 0xa
[0495.49] DevOnline: EOSSDK-LogEOSRTC: LibRTCCore: LibRtc::FStatisticsService::GetConferenceStats. Collecting statistics is already in progress
...
[0499.43] Error: EOSSDK-LogEOSRTC: RTCRoom [46190D3611EE65218B3F669003816124-0 bf1...37b] MercuryOutputStream_Create unable to start with those channels and sample rate
[0499.43] Error: EOSSDK-LogEOSRTC: RTCRoom [46190D3611EE65218B3F669003816124-0 bf1...37b] StartRendering failed

XAudio2 Error: Result -> 0x800401F0 mapping to CO_E_NOTINITIALIZED, the device not being initialized would make sense if it exited early on.

Finally when actually quitting the game, log entries are prefixed "exit"

[0040.32] Exit: Preparing to exit.
[0040.41] Exit: Game engine shut down
[0040.45] Exit: Windows client shut down
[0040.46] Exit: AK Audio shut down.
[0045.25] Exit: Object subsystem successfully closed.
[0046.89] Exit: Exiting.
[0046.89] Log: Log file closed, 07/10/2023 18:11:27

So it would seem this super early XAudio2 exit is unexpected.

Taking a closer look at the EOSSDK, it seems to use some version of the Google WebRTC implementation: https://webrtc.googlesource.com/ which I don't think mentions xaudio. However the SDK clearly does.
https://dev.epicgames.com/docs/game-services/voice#implementing-the-voice-interface-on-windows
Specifically xaudio2_9. Which matches up with the proton logs I got.

Some other debugging info... Game logs are in:
compatdata/252950/pfx/drive_c/users/steamuser/My Documents/My Games/Rocket League/TAGame/Logs/Launch.log

You can get those same logs in your proton log with: warn+seh in WINEDEBUG.
Some ole error confirms the XAudio2 CO_E_NOTINITIALIZED error.

1868.222:0140:err:ole:com_get_class_object apartment not initialised
1868.222:0140:warn:seh:OutputDebugStringA "[0210.01] Error: EOSSDK-LogAudioMixer: XAudio2 Error: Result -> 0x800401F0: UNKNOWN (line: 436)\r\n"
1868.222:0140:warn:seh:dispatch_exception "[0210.01] Error: EOSSDK-LogAudioMixer: XAudio2 Error: Result -> 0x800401F0: UNKNOWN (line: 436)\r\n"
1868.222:0140:warn:seh:OutputDebugStringA "[0210.01] DevOnline: EOSSDK-LogEOSRTC: RTCRoom [D260D4D211EE65C53CDC2C854F78CFAD-0 bf1...37b] QueryOutputDevices failed 2147483647\r\n"
1868.222:0140:warn:seh:dispatch_exception "[0210.01] DevOnline: EOSSDK-LogEOSRTC: RTCRoom [D260D4D211EE65C53CDC2C854F78CFAD-0 bf1...37b] QueryOutputDevices failed 2147483647\r\n"
1868.222:0140:warn:seh:OutputDebugStringA "[0210.01] DevOnline: EOSSDK-LogEOSRTC: RTCRoom [D260D4D211EE65C53CDC2C854F78CFAD-0 bf1...37b] The specific output device id '{0.0.0.00000000}.{FD47D9CC-4218-4135-9CE2-0C195C87405B}' has not been found. The default device index '-1' will be used instead of it\r\n"
1868.222:0140:warn:seh:dispatch_exception "[0210.01] DevOnline: EOSSDK-LogEOSRTC: RTCRoom [D260D4D211EE65C53CDC2C854F78CFAD-0 bf1...37b] The specific output device id '{0.0.0.00000000}.{FD47D9CC-4218-4135-9CE2-0C195C87405B}' has not been found. The default device index '-1' will be used instead of it\r\n"
1868.223:0140:err:ole:com_get_class_object apartment not initialised
1868.223:0140:warn:seh:OutputDebugStringA "[0210.01] Error: EOSSDK-LogAudioMixer: XAudio2 Error: Result -> 0x800401F0: UNKNOWN (line: 850)\r\n"
1868.223:0140:warn:seh:dispatch_exception "[0210.01] Error: EOSSDK-LogAudioMixer: XAudio2 Error: Result -> 0x800401F0: UNKNOWN (line: 850)\r\n"
1868.223:0140:warn:seh:OutputDebugStringA "[0210.01] Error: EOSSDK-LogEOSRTC: RTCRoom [D260D4D211EE65C53CDC2C854F78CFAD-0 bf1...37b] unable to get output device information by index[-1]. 0xa\r\n"
1868.223:0140:warn:seh:dispatch_exception "[0210.01] Error: EOSSDK-LogEOSRTC: RTCRoom [D260D4D211EE65C53CDC2C854F78CFAD-0 bf1...37b] unable to get output device information by index[-1]. 0xa\r\n"

When changing audio device during the match it indeed resolves the issue. Though I couldn't find any noteworthy logs by the game to confirm the switch. Just the absence of errors and some logs about SaveData. Which I assume has to do with persisting the settings change.

On successfully switching device, first mmdevapi gets hammered to enumerate devices, xaudio2 gives one warning: warn:xaudio2:xaudio2_initialize Processor affinity not implemented in FAudio and then a giant wall of xaudio2 traces for all the buffers processed.

Final log settings I ended up running were:
PROTON_LOG=1 WINEDEBUG="+timestamp,warn+seh,warn+mmdevapi,warn+pulse,+loaddll,warn+xaudio2,warn+ole" %command%

:shrug: that's about where I run out of expertise, hope this helps anyone with more wine experience debug.

All I have right now is a suspicion that:

• The game's device selection code differs when joining the match vs changing settings in-game.
• And the device selection on join fails with this uninitialized com apartment.

Why this fails, I'm not sure. Perhaps the xaudio2 dll drops a reference to mmdev too soon. Perhaps the game is bugged. Perhaps trying to use your "SaveData" audio settings is non-deterministic and fails to grab that particular device or fallback. Maybe the XAudio2 that "exits" 11 seconds after starting the game is the handle it tries to use to init on join? :shrug:

However fortunately it should be easy to reproduce. This XAudio2 Error: Result -> 0x800401F0 can be observed 100% of the time when joining any match, regardless of other players talking or even joining the voice channel.

As a note for those playing the Steam edition of Rocket League in 2024, I've only had a flawless time running it in Proton Experimental or the latest GE-Proton build. This is likely due to attempts by EGS to kick Linux users off online.

Replying to https://github.com/ValveSoftware/Proton/issues/3521#issuecomment-2121045115

Same issue here

Using the newly released Proton 10 (as well as ProtonGE 10.3), Rocket League freezes in fullscreen mode

Correction: It only freezes when switching windowing modes, so if it's already in fullscreen mode while starting, it still runs. Also while in fullscreen, the mouse is offset so I have to click ~100 pixels lower than where the buttons are (I experienced this in another game as well). In borderless mode, there is no option to choose my full monitor resolution, so I am stuck on a lower resolution (2048x1152 instead of 2560x1440).

In all three windowing modes (fullscreen, borderless, windowed), the game appears blurry compared to running with Proton 9 or on Windows.

Here's the log: steam-252950.log

And the gist: Steam Runtime Diagnostics

@ahmouse15 Thank you for the details! As an additional point of clarification - could you please also give the output of "xrandr --listmonitors" on your system? This bug seems like it might be quite hardware specific as well :)

@alasky17

ahmouse@excelsior ~ $ xrandr --listmonitors
Monitors: 1
 0: +*DP-3 2560/597x1440/336+0+0  DP-3

To clarify, I don't experience any of these issues with Proton 9

I am unable to make this game works, not sure if issue is at my side can someone help here a bit to figure out?

Launch Options:
PROTON_LOG=1 mangohud --dlsym gamemoderun %command%
but tried with PROTON_LOG=1 %command% with the same fate.

Proton Logs:

• File: steam-252950.log

[...]
1558787.333:0120:0124:trace:loaddll:build_module Loaded L"C:\\windows\\system32\\wineopenxr.dll" at 00007F6B940C0000: builtin
warn:  OpenXR: Unable to get required Vulkan instance extensions size
info:  Enabled instance extensions:
info:    VK_EXT_surface_maintenance1
info:    VK_KHR_get_surface_capabilities2
info:    VK_KHR_surface
info:    VK_KHR_win32_surface
wine client error:124: write: Invalid argument

@nolddor Hi there. How does it behave with regular Proton? We don't support GE-Proton.

Hey @Blisto91, indeed problem is reproducible in the same way with regular Proton, see below:

Steam Runtime Diagnostics:

• steam-runtime-system-info.json

Compatibility Tool:
Proton 9.0-4

Launch Options:
PROTON_LOG=1 %command%

Proton Logs:

• steam-252950.log

[...]
1594204.606:0128:012c:trace:loaddll:build_module Loaded L"C:\\windows\\system32\\wineopenxr.dll" at 00007FA11A220000: builtin
warn:  OpenXR: Unable to get required Vulkan instance extensions size
info:  Enabled instance extensions:
info:    VK_EXT_surface_maintenance1
info:    VK_KHR_get_surface_capabilities2
info:    VK_KHR_surface
info:    VK_KHR_win32_surface
wine client error:12c: write: Invalid argument

Actual Behaviour:
Game refuse to start.

Known workaround:
Using PROTON_USE_WINED3D=1 make the game to start.

did you see something wrong at my logs?

@alasky17 In case you're interested, ProtonGE provided a fix for the mouse offset issue, what is seemingly caused by fractional scaling.

Replying to https://github.com/ValveSoftware/Proton/issues/3521#issuecomment-2121045115

Same issue - if I press options to join, sometimes one, two or even three cars join the lobby. The controller then controls all cars simultaneously, its input is duplicated or even quadrupled. It's quite annoying, since that 'options' to join can't be remapped, just like opening the menu. Also stops queue etc.

Is there anything I can try to help you reproduce this issue?

I'm using a PS5 dualsense controller on Steam, without Steam Input.

@CaptaiNiveau does the issue happen on offline play, do you have to be at some specific screens for the issue to be able to manifest? Does the issue also happen with steam input enabled? In what proton versions have you seen the issue?

@nolddor Do you still have issues launching the game? If so, does the game crash on proton 8 as well?

@simifor unable to try until end Sept on holidays with no access to PC ;(

Last time I tried issue was there, no idea with proton 8

@tyrohellion if you switch over to proton experimental bleeding-edge the performance should be better compared to proton 10 and normal experimental.

@nolddor that's fine

@takardo the game works on my end.
I'm guessing that by "I couldn't get this to work" you mean the proton log, can you share the launch parameter you have for the game? Also, try running steam from your terminal, and check what logs it gives you when trying to launch rocket league (these aren't equivalent to the proton log but better than nothing)

@simifor Yeah, I feel silly for this. Sorry. After I made the issue I realized I needed to right click the game and set the proton version there as I was doing it in the global steam setting. Can delete my issue or disregard. sorry about this and thank you.

Another fun thing I found: When I press Alt+F4 in rocket league, steam will indefinitely show the game as "running" and I can then click "stop" in my library to close it, even though no windows are visible.

Another fun thing I found: When I press Alt+F4 in rocket league, steam will indefinitely show the game as "running" and I can then click "stop" in my library to close it, even though no windows are visible.

Are you sure you don't have anything else running in the prefix (e.g. BakkesMod)?

Compatibility Report

• Name of the game with compatibility issues: Rocket League
• Steam AppID of the game: 252950

System Information

• GPU: NVIDIA GeForce RTX 2070 SUPER
• Video driver version: nvidia 580.105.08
• Kernel version: 6.17.9-arch1-1
• Link to full system information report as Gist: https://gist.github.com/MarcusOtter/6b96705976ac9f19ccccb30ce374957e
• Proton version: 765195901 experimental-10.0-20251208

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

Proton logs:
steam-252950.log

Rocket League logs:
Launch.log

Symptoms

When launching rocket league it was not able to connect to Epic Online Services, see images below.

1	2

For search purposes:

You are not connected to Epic Online Services. Would you like to reconnect?

Having problems communicating with Epic Online Services. Please try again in a few minutes. (Error: 0)

The game worked just fine in offline mode, but I needed online mode to work.

I spent a couple days trying to make sense of this, synchronizing time, disabling firewalls, changing DNS, using VPN, etc etc to no avail.

In the attached logs there are some hints of what's happening, namely:

(Launch.log)

[0012.35] DevOnline: EOSSDK-LogEOSAuth: FAccountPortalBrowserManager::Init: Failed to register overlay: EOS_NotConfigured

...

[0020.80] DevOnline: EOSSDK-LogEOS: Error response received from backend. ServiceName=[OAuth], OperationName=[TokenGrantv2], Url=[<Redacted>], HttpStatus=[400], ErrorCode=[errors.com.epicgames.oauth.corrective_action_required], NumericErrorCode=[18206], ErrorMessage=[Corrective action is required to continue.], CorrId=[EOS-<Redacted>]
[0020.83] DevOnline: EOSSDK-LogEOSAuth: UserAuthGenerated: Account Portal overlay failed to load for corrective action; falling back to browser based flow
[0020.98] DevOnline: EOSSDK-LogEOSAuth: UserAuthGenerated: Account Portal overlay failed to load for device auth continuation; falling back to browser based flow

...

[0021.71] DevOnline: EOSSDK-LogEOS: Error response received from backend. ServiceName=[OAuth], OperationName=[TokenGrantv2], Url=[<Redacted>], HttpStatus=[400], ErrorCode=[errors.com.epicgames.account.oauth.authorization_pending], NumericErrorCode=[1012], ErrorMessage=[The authorization server request is still pending as the end user has yet to visit and enter the verification code.], CorrId=[EOS-<Redacted>]

...

[0049.38] AuthEpicVerbose: Login failed for player '0' with error 'OSCS_NotConnected'
[0049.38] GFxEpicLogin: HandleLoginError Error: EOSFailedToConnect EOSFailedToConnect
[0049.38] AuthEpicCritical: Lost Epic connection during login

Clearly it was trying to open my browser, some online searches suggest it was to agree to a EULA, but it definitely never opened my browser. xdg-open https://example.com works fine for me so I assume something is wrong with how Rocket League is trying to open my browser.

Workaround

The only workaround I could think of was to install Rocket League on a Windows computer and try to accept the EULA there, and sure enough, as soon as I opened Rocket League on my Windows laptop, it immediately tabbed down and sent me to my browser to sign some EULA thing for EU citizens. After accepting that EULA on Windows, the error went away on Linux.

Reproduction

This feels like it will be hard to reproduce. But it goes something like:

• Create new Steam + Epic Games accounts and link them together, make sure they are EU citizens and that you are connecting from the EU
• Install and open Rocket League
• See error

Now I won't be able to reproduce it any more on this account, but I did try with another account which also had the same problem so I will be able to help debugging if needed.

Other

Really not sure where this bug is supposed to be logged, but it works on Windows with my account, and I can't seem to figure out anything wrong with my machine or network, so it feels like something is wrong with Proton, let me know if that is a flawed assumption.

New EAC update landed and it seems for non English locale systems it doesnt load EAC unless you force English locale.

EAC launcher log with my default locale:

[22:15:31:064] [Windows] [EAC Bootstrapper] [Info] System locale: 'tr_TR'.
[22:15:31:065] [Windows] [EAC Bootstrapper] [Info] Localization file loaded, using 'tr_tr'.
[22:15:31:066] [Windows] [EAC Bootstrapper] [Err!] Could not locate font file: 'C:\windows\Fonts\Segoeui.ttf' on disk, falling back to en_us.
[22:15:31:066] [Windows] [EAC Bootstrapper] [Err!] Failed in loading font from file: 'C:\windows\Fonts\Segoeui.ttf'.
[22:15:31:066] [Windows] [EAC Bootstrapper] [Err!] Failed to load the Easy Anti-Cheat Game Launcher's assets.
[22:15:31:066] [Windows] [EAC Bootstrapper] [Info] Localization file loaded, using 'en_us'.
[22:15:31:066] [Windows] [EAC Bootstrapper] [Err!] Failed to load the embedded resources.

With LANG=en_US.UTF-8 environment variable:

[22:19:02:015] [Windows] [EAC Bootstrapper] [Info] System locale: 'en_US'.
[22:19:02:015] [Windows] [EAC Bootstrapper] [Info] Localization file loaded, using 'en_us'.
[22:19:02:038] [Windows] [EAC Bootstrapper] [Info] Embedded resources successfully loaded.
[22:19:02:039] [Windows] [EAC Bootstrapper] [Info] Will use the icon extracted from the game executable.
[22:19:02:050] [Windows] [EAC Bootstrapper] [Info] System name: 'linux64'.
[22:19:02:050] [Windows] [EAC Bootstrapper] [Info] Loader initializing with bootstrapper version 1.9.3, architecture: x86-64.
[22:19:02:051] [Windows] [EAC Bootstrapper] [Info] Loader component initialized.

Replying to https://github.com/ValveSoftware/Proton/issues/3521#issuecomment-4339514395

For now you can edit tr_tr.cfg and remove all mention of segoeui font