Arduino does not recognize library files anymore

Development Tools IDE 2.x
1

Arduino IDE 2.3.6 worked fine until yesterday but now Arduino IDE does not recognize the installed libraries anymore in the folder Sketchbook/libraries, but the files are all there.

I checked the preferences setting for the location of the sketchbook folder but that is OK. Loading a sketch from the sketchbook folder works fine, but compiling the sketch gives a message that it cannot find the library which is used in the sketch. Checking the library manager and selecting “installed” does not show any installed library.

Who can help me out?

2

I had that happen once, try just quitting and re-starting the IDE.

3

Check the arduino-cli.yaml (use notepad or other simple editor) and make sure the User path is the same as your preferences Sketchbook Location