how to fix unity error CS0103

[aristod00]

some older classes require a specific library . the main problem is that I don't remember which Library was connected Once Upon a time , and I can't even find out which library that class needs , because when "go to base"(or "view call hierarchy" , "find all references")in visual studio 2022, there are no search results . it is also not colored . maybe I got something wrong ? I looked at other issues on this topic but it didn't help me

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