I get the attached error when trying to open "Theme options". I don't think its a bug since it works totally fine on my dev system (which is totally different, different server, different php version, etc.).
Attached you can find the error.
Any idea how this is caused?
I did not change anything on the themes. It's totally out of the box.
We need to know what $file really is here. Weirdly it's not included in the error message. You can also contact your hosting provider about open_basedir restriction.