The class Diagnostics couldn't be found in the file 'C:\inetpub\wwwroot\PIWIK/plugins/Diagnostics/Diagnostics.php'

This message has suddenly started to appear when trying to access the server.

The software is installed on a VM in the Azure cloud and has been running fine 'til today. to the best of my knowledge, we have not updated the software though the regular Windows updates would have been run.

We have two ‘on prem’ copies running - the second (also on a VM in Azure , but in a different availability zone) is running fine.

Can any one tell me how to run the core:clear cache I have seen online in a Windows environment?


At first I would check how your plugins/Diagnostics/Diagnostics.php. It should look like this.

How to run the console depends on your operating system and your php setup. But it will look something like that (inside your C:\inetpub\wwwroot\PIWIK folder):

php ./console core:clear-caches