This answer quotes ChatGPT
The error message is that the database connection failed. The error message "Unable to connect" indicates that the database cannot be connected. Possible causes include:
1. The database server is not started.
2. The IP address or port number is incorrect.
3. The firewall is blocking the connection.
4. The database account or password is incorrect.
You need to check that the database connection configuration is correct. For example:
1. Check whether the database server is started.
2. Check whether the IP address and port number of the database are correct.
3. Check whether a firewall blocks the connection.
4. Check whether the database account and password are correct.
Also, if you are using another database driver, such as pymysql or sqlite, you can check that the driver version is compatible with the database version.
