MSB6006: "csc.exe" exited with code -1073741819

[German998]

Files\dotnet\sdk\10.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error MSB6006: "csc.exe" exited with code -1073741819
tried reinstalling multiple Vs versions,Net everything couldnt solve it.

[markantill]

Same issue, I installed the .Net 10 SDK to do some dev work and after that every patcher with Synthesis is broken.

It doesn't matter what I select for Mutagen or Profile

e.g.

C:\Program Files\dotnet\sdk\10.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error MSB6006: "csc.exe" exited with code -1073741819. [C:\Users\mark_\AppData\Local\Temp\Synthesis\stnzkn5m.pku\Git\trkhtspj.cqc\Runner\AIOverhaulPatcher\AIOverhaulPatcher.csproj]
0 Warning(s)
1 Error(s)

Time Elapsed 00:00:22.63
2025-12-12 22:48:57.879 +00:00 [WRN] Encountered blocking overall error: "Synthesis" has a blocking error: (Fail, C:\Program Files\dotnet\sdk\10.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error MSB6006: "csc.exe" exited with code -1073741819.
C:\Program Files\dotnet\sdk\10.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error MSB6006: "csc.exe" exited with code -1073741819.), Halting: True

[markantill]

I uninstalled the .Net 10 SDK and went back to .Net 8 SDK and that worked again.
So that definately seems like the issue for me. I guess until there is a fix I will need to keep uninstalling before running, or try not to change my mod list as often.

[German998]

I uninstalled the .Net 10 SDK and went back to .Net 8 SDK and that worked again. So that definately seems like the issue for me. I guess until there is a fix I will need to keep uninstalling before running, or try not to change my mod list as often.

mkay i'll try that and let u know

[German998]

I uninstalled the .Net 10 SDK and went back to .Net 8 SDK and that worked again. So that definately seems like the issue for me. I guess until there is a fix I will need to keep uninstalling before running, or try not to change my mod list as often.

mkay i'll try that and let u know

nope still the same error

[markantill]

Does it still say Files\dotnet\sdk\10.0.101 in the error? If so 10 is still installed

[Noggog]

Yes, this is SDK 10 not playing well with Mo2

Copypasta from the discord news channel

Some people are reporting that SDK 10 does not play nice with Mo2 (even more than 9). You can uninstall 10 and install just 9 to get up and running.
I will be working towards a version that let's you control building/compiling timing more so that it can be avoided when running through mo2 entirely, which hopefully will sidestep a lot of the mo2 issues that have been popping up

Make sure SDK 10 is uninstalled and not showing up when you do a dotnet --info command (which is also printed to the synth logs on startup)

[markantill]

Well I need SDK 10 for other stuff and installing/uninstailling it was getting painful. I played with global.json to try and force it to run under 8 but that doesn't seem to work for me when launching from MO2 no matter where I put it.

In the end the only thing failing was the AI Overhaul patch so I pulled the repo and upgraded it locally to .Net 8 and used that version. I tried 10 but although I could build it directly it wouldn't build from Synthesis and logs were completly unhelpful so I settled on 8. Then everything worked for me.

[German998]

Alright i got it to work installig SDK: 9
and .NET 6,5,9,8
dunno but it works idc anmr.

[FN-FAL113]

Here's a solution that doesn't require removing .NET SDK 10 if you use it like me for development.

1. Install .NET 9 SDK
2. Navigate to C:\Program Files\dotnet\sdk
3. Rename .NET 10 sdk folder by adding .old

• 

4. Run synthesis, do your thing.
5. Rename .NET 10 sdk folder back by removing the suffix