Depending on how big your solution is, this can be a huge pain, but sometimes I have the same problem, and if I create a project showing errors, it goes away.
For example, only yesterday he could not find the Excel library for one of our small projects, and it was completely red, although nothing had changed, all the DLLs were found and mentioned, and nothing had been done explicitly. I just rebuilt this individual project, it compiled without errors, and the red bars immediately disappeared.
Chris doggett
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