Cache file 'double content' causes PHP error across entire site

[halftrainedharry]

Most likely the “flock mechanism (locking files for writing) does not work reliably” on your system.

Take a look at these (similar) issues for a solution:

Random blank page error 500 in manager & front

This is an indication that the flock mechanism (locking files for writing) does not work reliably. As a result the file gets written to twice. In your core/config/config.inc.php file, you can try adding use_flock to the $config_options array: $config_options = array( 'use_flock' => false, ); That will make MODX use a different method for file locking, which may work more reliably, especially on hosts with networked harddisks.

Strange and critical cache problem on shared hosting

In your config file in core/config/, find $config_options and add use_flock to it: $config_options = array( 'use_flock' => false ); It seems your shared server doesn’t provide a safe flock (file-lock) implementation, so by telling MODX not to use flock but a custom file locking approach that should become more reliable.