Intellisense stops working constantly (Windows)

[ptrc-c]

Type: Bug

I have a +10k LOC C project structured as a unity build, ie single translation unit compilation.

I'm only compiling "main.c", which includes a "includes.h" which in turn has all the source includes of the project.

Every time I open the project I need to open main.c then include.h, after that I need to manually click "Rescan Intellisense" after which intellisense works for a little while. But usually after couple of minutes symbols are lost again and I need to redo this process: open main.c, open includes.h then click "Rescan Intellisense". This has happened for over a year and happens constantly.

VSCode Version 1.105.1

EDIT: Grammar

Extension version: 1.28.3
VS Code version: Code 1.105.1 (7d842fb85a0275a4a8e4d7e040d2625abbf7f084, 2025-10-14T22:33:36.618Z)
OS version: Windows_NT x64 10.0.19045
Modes:

System Info

Item	Value
CPUs	AMD Ryzen 9 5900HX with Radeon Graphics (16 x 3294)
GPU Status	2d_canvas: enabled direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off trees_in_viz: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	31.42GB (22.17GB free)
Process Argv	. --crash-reporter-id 12781f6a-3be3-43b5-9a25-8cdd4f1840fa
Screen Reader	no
VM	0%

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[sean-mcmanus]

@ptrc-c We need more information and have not seen the issue you are describing. What does it say in the C/C++ logging pane with C_Cpp.loggingLevel set to "Debug"...is there some message about what is happening to the IntelliSense process, such as shutting down or crashing? When it's not working, are you able to attach a debugger to the cpptools-srv.exe process to get a call stack of a thread that might have useful information?