What does "MySQL server has gone away" mean?

The most common reason for the MySQL server has gone away error is that the query timed out and the connection is closed. This can happen when a MySQL query times out (i.e. a slow query).

We'd recommend running a MySQL check/optimization through phpMyAdmin to try and help with this error, to do this:

1. Sign in to the database you wish to optimise via phpMyAdmin. 
2. Select the database from the left-hand side menu. 
3. Select the tables you wish to optimise or select 'Check all'.
4. From the 'With selected:' dropdown menu, select 'Optimize table'.

The 'OPTIMIZE TABLE' query that's run reorganizes the physical storage of table data and associated index data, to reduce storage space and improve I/O efficiency when accessing the table.