This weekend I updated our test environment to CivCRM 5.10.0 running on Wordpress 5.0.3 and PHP 7.2.
I now find that if I use the CKEditor in e.g. Message Templates and click the Image button in the toolbar, then click Browse Server, the popup window comes back completely blank.
Likewise, if I try to upload a file, I get a popup saying "Incorrect Server Response" and the JS console shows
ckeditor.js:19 [CKEDITOR] Error code: filetools-response-error. {responseText: ""}
Similar errors I have found seem to suggest a file path or permissions error, but that they all seem to be correct as far as I can tell (and working fine on the production machine). PHP.ini memory limit is 2Gb, post_max_size is 1Gb and upload_max_filesize is 1Gb. I can't find any other errors being logged by the system.
Any thoughts as to where I can look next?
Steve