Akonadi Failed to connect to database

A couple of days ago, kmail stopped working.

When I try to launch akonadi_server, I get those error messages:

Failed to connect to database: Can't connect to local server through socket '/run/user/1000/akonadi/mysql.socket' (111) QMYSQL: Unable to connect


Xapian error
DatabaseOpeningError: Couldn't detect type of database.

I need some guidance find relevant information to resolve the issue.