1. Startup in Safe mode. https://support.apple.com/en-gb/HT201262 Choose the appropriate method.
To leave Safe Mode, click in the menu bar and choose “Restart”
Quote:
Safe mode prevents your Mac from loading certain software when it starts up, including login items,
system extensions not required by macOS,
and fonts not installed by macOS. It also does a basic check of your startup disk,
similar to using First Aid in Disk Utility.
And it deletes some system caches, including font caches and the kernel cache,
which will be created again automatically as needed.
2. Contact Apple.
If step posted above do not help,
Click inside the box to choose an option.
https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362