GUI Error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 26879033 bytes) File:/var/www/html/admin/libraries/BMO/Ajax.class.php:102

Hi,

One of our systems has started to show an error in the web interface - Allowed memory size of 536870912 bytes exhausted (tried to allocate 26879033 bytes) File:/var/www/html/admin/libraries/BMO/Ajax.class.php:102

Also when you try to apply settings you get an additional popup saying:

Error: Did not receive valid response from server

XHR response code: 500 XHR responseText: undefined jQuery status: error

As far as I'm aware the system is fully up to date and no changes were made before this problem.

The system has 4GB of RAM and is a virtual machine on Hyper-V (2012 R2). 

We have rebooted but the error returns.

Any ideas?

Thanks very much.