reason

The plugins plug-in failed

terms of settlement

1. Delete plug-in
user directory

\AppData\Roaming\Google\Android studio4.1\plugins

Find the directory and delete the corresponding plug-in
uninstall butterknife zelezny and install Android butterknife injections (support kotlin)
uninstall gsonformat and install gsonformatplus

2. The code is not highlighted and the error is not red

Errors don’t pop up, and they don’t pop up without this layout (I have already solved this problem)
don’t create an XML file according to the prompt

3. Code writing does not prompt

Click the file in the upper left corner to find the power save mode. If it is checked, you can cancel the check and restart studio.