That error message is a little misleading. It looks like Windows complains about long filenames, but in practice this usually means that the full command that US tries to run is too long (so not just the path to one file).

This often happens with large C/C++ projects (e.g. game engines or WoW cores) where a lot of include paths and define are passed on.

Important detail:
The registry key LongPathsEnabled=1 doesn't help with this problem, because that's only about NTFS path length, while this error usually comes from a Windows command-line length limit (~8191 characters).

Most common causes
1. Project path is too deep

For example, if your project is in something like:

C:\Users\you\Documents\VisualStudio\Projects\azerothcore-wotlk-npcbots-custom-build\...

Then the total compile command becomes gigantic.

Solution (usually the fastest):

Move the project to something short:

C:\dev\acore

or

D:\ac

This solves the problem surprisingly often directly.

2. Too many include directories

Visual Studio can generate hundreds of inclusive paths in large projects such as:

/I"C:\...\dep1"
/I"C:\...\dep2"
/I"C:\...\dep3"

Together they can make command > 8191 chars.

Fix:

Use response files or shortened paths, but that usually requires an adjustment in the buildsystem (CMake / premake / etc).

3. Resource compiler (rc.exe) path problem

Sometimes U.S. rc.exe doesn't like it or tries to start it with an absurd path.

See if he exists.

C:\Program Files (x86)\Windows Kits\10\bin\...\x64\rc.exe

4. Visual Studio environment bug

Sometimes it helps to reset the US Developer Command Prompt.

Run:

"%ProgramFiles%\Microsoft Visual Studio\2022\Community\Common7\Tools\VsDevCmd.bat"

Quick diagnosis (do this first)

Check the Output window (not Error List) and look for the line where rc.exe is started.

You usually see something like:

rc.exe /I ... /I ... /D ... /fo ...

If that rule is absurdly long → then that's the problem.

What I suspect in your case

Because you were previously working with AzerothCore / TrinityCore / WoW builds:

These projects are notorious for having huge inclusion chains.

Combine that with a long project folder and rc.exe blows out.

My guess is 90% chance your path is just too deep.

Fast test (30 seconds)

Clone or move your project to:

D:\ac

Open the .sln again and compile.

When it suddenly works → bingo.

If you want

Mail me.

The first rc.exe error line from the Output tab

The path where your project is

Then I can quickly see where the length explodes.
Visual Studio can sometimes make that really epic drama.