I played this game for 50h in the last month. The from one day to the next it stopped working. If I start the game it tries to load, then exits immediately. I believe there was a game update - but I'm not 100% sure. I tried already to validate the local files, with no error or change.

The proton.log has the following entry last:

WARNING: lavapipe is not a conformant vulkan implementation, testing use only. Fossilize INFO: Overriding serialization path: "/mnt/disk/games/steam/steamapps/shadercache/292030/fozpipelinesv6/steamapprun_pipeline_cache". info: DXVK: Read 1771 valid state cache entries info: DXVK: Using 16 compiler threads 2381.798:0134:0138:trace:loaddll:build_module Loaded L"Z:\mnt\disk\games\steam\steamapps\common\The Witcher 3\bin\x64\GFSDK_HairWorks.win64.dll" at 000000006C660000: native info: Presenter: Actual swap chain properties: info: Format: VK_FORMAT_B8G8R8A8_UNORM info: Present mode: VK_PRESENT_MODE_IMMEDIATE_KHR info: Buffer size: 3440x1440 info: Image count: 3 info: Exclusive FS: 1 warn: DXGI: MakeWindowAssociation: Ignoring flags info: Presenter: Actual swap chain properties: info: Format: VK_FORMAT_B8G8R8A8_UNORM info: Present mode: VK_PRESENT_MODE_FIFO_KHR info: Buffer size: 3440x1440 info: Image count: 4 info: Exclusive FS: 1 2382.055:0134:0138:fixme:pulse:AudioSessionControl_RegisterAudioSessionNotification (000000006C3F88D0)->(0000000004508648) - stub 2382.061:0134:0218:fixme:avrt:AvSetMmThreadCharacteristicsW (L"Audio",00000001060AFE34): stub 2382.061:0134:0218:fixme:avrt:AvSetMmThreadPriority (0000000012345678)->(1) stub 2382.063:0134:0220:trace:seh:dispatch_exception code=406d1388 flags=0 addr=000000007B0124BE ip=000000007B0124BE tid=0220 2382.063:0134:0220:trace:unwind:dispatch_exception info[0]=0000000000001000 2382.063:0134:0220:trace:unwind:dispatch_exception info[1]=00000003d6477fc0 2382.063:0134:0220:trace:unwind:dispatch_exception info[2]=00000000ffffffff 2382.063:0134:0220:warn:seh:dispatch_exception Thread ffffffff renamed to "ScaleformSideLoader" 2382.063:0134:0220:trace:seh:call_vectored_handlers calling handler at 000000027104AAF0 code=406d1388 flags=0 2382.063:0134:0220:trace:seh:call_vectored_handlers handler at 000000027104AAF0 returned ffffffff X connection to :99.0 broken (explicit kill or server shutdown). pid 33644 != 33643, skipping destruction (fork without exec?)