Exactly the same issue with http://www.stmaryoftheangels.org.uk just now. “Warning: preg_match(): Compilation failed: unrecognized character after (?< at offset 4”. If you log out of the admin panel you can’t get back in.
Thankfully backed up the Files and DB beforehand so could roll back to prior version and this fixed the issue. I’m not going to upgrade to 4.9 until the issue is fixed, either Easily or with ww.wp.xz.cn.
Fixed it. I needed to create and give 777 permissions to the Upload folder. Wow and I thought that weird path was to blame!!!!
OK – after I looked at it it isn’t just an issue with Media but also Plug-ins and virtually anything that relates to the WP-content directory. Almost as if the path for this directory is wrong, even though the Settings/Misc value is correct? Can anyone help or do I need to re-install WordPress?
