Godot.4.4.2.stable.arch_linux
Running Godot test mode floods my debugger output with this error:
E 0:00:00:0764 _save_to_cache: Condition "f.is_null()" is true.
<C++ Source> servers/rendering/renderer_rd/shader_rd.cpp:470 @ _save_to_cache()
Running the engine on Linux, I tried to check permissions of my .godot/cache directory but everything seems fine (it’s 775 by default, but putting them at 777 doesn’t change anything).
Help? I searched other topics adressing this error in the forums and there was nothing, am I a single case? 
This Github issue suggests it may be due to the directory path of your project. Is it very long or unusual in some way? Double check the directory permissions too.
Yes, the project is located at the bottom of a tree of several folders into my external HDD.
The permissions of the cache folder definitely makes it accessible to Godot.
Sorry, I accidentally deleted previous post.
Have you found a fix?
Nope, sorry…
Who is the owner of the folder? And is the user starting Godot the same owner?