2.6.1.3.3. Database connection error
If you encounter a database connection error, first check that the connection details you are using are correct (host, database name, database username, and password). You can find the current database access credentials using the instructions.
If the credentials are correct but you still cannot access the database, the issue may be that the database connection limit has been reached. Typically, in such situations, database access comes and goes intermittently. To resolve the issue, you need to identify the possible causes of a high number of database connections and address them.
If you are able to connect to the database, you can view the list of current connections and forcibly terminate any unnecessary processes. You can do this, for example, using phpMyAdmin or HeidiSQL.