Overall, very pleased with all your work on the Endless franchise, and thank you for the deal with Endless Legend for both new DLC! Also, thank you for supporting the Mac with your games as well, it is much appreciated.

• Issue
  After installing the Supremacy DLC and updating the app to the latest version on Steam, the game always crashes when choosing Exit to Desktop from the main menu, complete with the macOS system error report mechanism kicking in. I see the Exit feature has had issues a lot over the versions, although typically it's been failing to exit the game rather than a crash out. Hope this isn't too much of a redundant post.
  
  
• Specs
  macOS 10.13.6 "High Sierra", Mac Pro, 64-bit, 3.7GHz quad-core Intel Xeon E5, 32GB RAM, two linked AMD FirePro D700 video cards with 6GB each
  
  
• Version
  Endless Space 2 with Vaulters and Supremacy V1.3.3 S5 GOLD-Public (64-bit)
  
  
• Game save
  N/A. Don't have to save a game for this, it always happens even if I just launch, don't play, and Exit immediately.
  
  
• Player.log
  I won't post log files in a public forum, but I am happy to send your tech support all relevant logs and the system profile if you give me a place to send it. There are several potential lines of note:
  
  Filename: /Users/builduser/buildslave/unity/build/artifacts/generated/common/runtime/DebugBindings.gen.cpp Line: 51)
  
  Fallback handler could not load library ~/Library/Application Support/Steam/SteamApps/common/Endless Space 2/EndlessSpace2.app/Contents/Frameworks/MonoEmbedRuntime/osx/user32
  Fallback handler could not load library ~/Library/Application Support/Steam/SteamApps/common/Endless Space 2/EndlessSpace2.app/Contents/Frameworks/MonoEmbedRuntime/osx/libuser32.dylib
  
  The above entry is followed by a lot of "Fallback handler could not load library" messages for a whole pile of Mono framework .bundle files.
  
  
  (Filename: /Users/builduser/buildslave/unity/build/artifacts/generated/common/runtime/DebugBindings.gen.cpp Line: 51)
  
  WARNING: Shader Unsupported: 'Amplitude/ParticleRenderUIDebug' - Pass '' has no vertex shader
  ERROR: Shader Shader is not supported on this GPU (none of subshaders/fallbacks are suitable)
  WARNING: Shader Unsupported: 'Amplitude/ParticleRenderUIDebug' - Setting to default shader.
  -------- Shader compilation failed
  
  Lots of OpenGL errors in here, complete with a ton of OpenGL details, such as:
  
  -------- failed compiling:
  vertex shader
  WARNING: 0:3: extension 'GL_ARB_shader_storage_buffer_object' is not supported
  WARNING: 0:4: extension 'GL_ARB_shader_image_load_store' is not supported
  ERROR: 0:24: 'buffer' : syntax error: syntax error
  
  Note: Creation of internal variant of shader 'Amplitude/Galaxy/DiplomaticScanViewPastEncounter' failed.
  WARNING: Shader Unsupported: 'Amplitude/Galaxy/DiplomaticScanViewPastEncounter' - Pass '' has no vertex shader
  ERROR: Shader Shader is not supported on this GPU (none of subshaders/fallbacks are suitable)
  WARNING: Shader Unsupported: 'Amplitude/Galaxy/DiplomaticScanViewPastEncounter' - Setting to default shader.
  -------- Shader compilation failed
  
  I also see
  
  OPENGL NATIVE PLUG-IN ERROR: GL_INVALID_ENUM: enum argument out of range
  
  near this line:
  
  (Filename: /Users/builduser/buildslave/unity/build/Runtime/GfxDevice/opengles/GfxDeviceGLES.cpp Line: 299)
  
  That line 299 has a few goodies such as:
  
  OPENGL NATIVE PLUG-IN ERROR: GL_INVALID_OPERATION: Operation illegal in current state
  
  
  There are also a ton of entries for Mono at both the GfxDeviceGLES.cpp line 299, and DebugBindings.gen.cpp line 51, such as:
  
  Fallback handler could not load library ~/Library/Application Support/Steam/SteamApps/common/Endless Space 2/EndlessSpace2.app/Contents/Frameworks/MonoEmbedRuntime/osx/libsteam_api
  Fallback handler could not load library ~/Library/Application Support/Steam/SteamApps/common/Endless Space 2/EndlessSpace2.app/Contents/Frameworks/MonoEmbedRuntime/osx/libsteam_api_dotnetwrapper
  
  With a pile of similar MonoEmbedRuntime failures to laod libraries.
  
  
  And here we go, the big error right at the Exit moment, the game shutdown:
  
  (Filename: /Users/builduser/buildslave/unity/build/artifacts/generated/common/runtime/DebugBindings.gen.cpp Line: 51)
  
  Receiving unhandled NULL exception
  Obtained 12 stack frames.
  #0  0x0000010053c582 in ResourceManager::GetPathRange(std::string const&)
  #1  0x0000010071c14f in Resources_CUSTOM_Load(MonoString*, MonoObject*)
  #2  0x0000012d0ac12b in  (wrapper managed-to-native) UnityEngine.Resources:Load (string,System.Type) + 0x6b (0x12d0ac0c0 0x12d0ac146) [0x10cf2dcc0 - Unity Root Domain]
  #3  0x0000010cf6eaee in  (wrapper runtime-invoke) object:runtime_invoke_virtual_void__this__ (object,intptr,intptr,intptr) + 0x5e (0x10cf6ea90 0x10cf6eb55) [0x10cf2dcc0 - Unity Root Domain]
  #4  0x00000101f54fa5 in mono_gc_run_finalize
  #5  0x00000101f564d4 in finalizer_thread
  #6  0x00000101fc9965 in start_wrapper
  #7  0x00000101ff998a in thread_start_routine
  #8  0x0000010201fce6 in GC_start_routine
  #9  0x007fff77d95661 in _pthread_body
  #10 0x007fff77d9550d in _pthread_body
  #11 0x007fff77d94bf9 in thread_start
  Stacktrace:
  
    at (wrapper managed-to-native) UnityEngine.Resources.Load (string,System.Type) <0x0006b>
    at (wrapper managed-to-native) UnityEngine.Resources.Load (string,System.Type) <0x0006b>
    at UnityEngine.Resources.Load (string) <0x0001e>
    at AgeManager.FindDynamicTexture (string,bool,bool) <0x00340>
    at Amplitude.Unity.Gui.Gui.GetTexture (Amplitude.Unity.Gui.GuiElement,Amplitude.StaticString,UnityEngine.Texture2D) <0x00156>
    at Gui.GetTexture (Amplitude.Unity.Gui.GuiElement,Amplitude.StaticString,UnityEngine.Texture2D) <0x00069>
    at PlanetCircleItem.Refresh (EntityExploration/State) <0x000dc>
    at PlanetCircleItem.Planet_OnMiningProbeChanged (object,System.EventArgs) <0x0005e>
    at Planet.SetMiningProbe (MiningProbe) <0x00046>
    at MiningProbe.Dispose (bool) <0x00035>
    at Amplitude.Unity.Simulation.SimulationObjectWrapper.Finalize () <0x00020>
    at (wrapper runtime-invoke) object.runtime_invoke_virtual_void__this__ (object,intptr,intptr,intptr) <0x0005d>
  
  Native stacktrace:
  
      0   libsystem_kernel.dylib              0x00007fff77bcdb66 __pthread_kill + 10
      1   libsystem_c.dylib                   0x00007fff77b291ae abort + 127
      2   EndlessSpace2                       0x00000001006a01d4 _Z12HandleSignaliP9__siginfoPv + 36
      3   libmono.0.dylib                     0x0000000101f29c09 mono_chain_signal + 75
      4   libmono.0.dylib                     0x0000000101e71a72 mono_sigsegv_signal_handler + 210
      5   libsystem_platform.dylib            0x00007fff77d8bf5a _sigtramp + 26
      6   ???                                 0xfd00000070001006 0x0 + 18230571293474820102
      7   EndlessSpace2                       0x000000010071c14f _Z21Resources_CUSTOM_LoadP10MonoStringP10MonoObject + 191
      8   ???                                 0x000000012d0ac12b 0x0 + 5050646827
      9   ???                                 0x000000010cf6eaee 0x0 + 4512475886
      10  libmono.0.dylib                     0x0000000101f54fa5 mono_gc_run_finalize + 881
      11  libmono.0.dylib                     0x0000000101f564d4 finalizer_thread + 410
      12  libmono.0.dylib                     0x0000000101fc9965 start_wrapper + 457
      13  libmono.0.dylib                     0x0000000101ff998a thread_start_routine + 218
      14  libmono.0.dylib                     0x000000010201fce6 GC_start_routine + 96
      15  libsystem_pthread.dylib             0x00007fff77d95661 _pthread_body + 340
      16  libsystem_pthread.dylib             0x00007fff77d9550d _pthread_body + 0
      17  libsystem_pthread.dylib             0x00007fff77d94bf9 thread_start + 13
  
  Debug info from gdb:
  
  
  =================================================================
  Got a SIGABRT while executing native code. This usually indicates
  a fatal error in the mono runtime or one of the native libraries
  used by your application.
  =================================================================
  
  pid 12368 != 12237, skipping destruction (fork without exec?)
  
  Bascially OpenGL and Mono seem to produce the most error lines. Speaking of the Mono Framework... I see Endless Space 2 is using Mono 4.8.0. Does Endless Space 2 use a higher version of Mono if it sees one? I checked the Mono site and the latest release is 5.14.0. Your Mac support suggests upgrading Mono can fix errors, so I will try that.
  
  
• Diagnostics.*.html
  I am not comfortable posting these in a public forum for the same reasons as log files. These contain real account names and sometimes other details not for public posting. I am happy to send them to your support staff directly. Looking in the latest HTML files from the last couple tries, there are no Warning or Error-level entries. Actually no entries at all for Endless Space 2, these are empty for the last couple versions.
  
  
• Screenshots
  N/A
  
  
• Multiplayer
  I have not tried multiplayer.

 We will also ask you to link your Steam account, this way we can ensure you are playing on an updated client and not an outdated and buggy pirate version...

Not too comfortable with linking accounts across services either... Though I do get why you would want to see this, I don't do this anywhere at this time - it's better security to keep accounts separate even if it is inconvenient. I also don't mind avoiding all that marketing profiling and data mining that happens when you link accounts! Advertising bugs me. :P If there is another way we can prove we are using a legit, updated Steam client and game, that would be great!

Update: Ugrading to Mono 5.14.0 did not solve the problems. Still crashes on exit. There is also a memory leak after several hours of plahying, where the entire macOS freezs and becomes unresposive. But that's another issue - and it seems to lack the paper trial in the logs!

Ug, apologies for the typos...