Malware scan failing

Some progress – I have established it is something in the theme that is doing it. Works when i move the theme out and just use the default 2017 theme.

If I bring the theme back into the themes folder but do not activate it, the malware scan runs. If I activate the theme the error comes back. It is like something in the theme must be interfering with wp-admin.However, where I also use this theme it doesn’t create the same behaviour. I am heading for functions.php to see if there is something in there that should be.

OK – I have found it !! However the cause is not obvious to me. I did a diff on one functions.php file that works and another that doesn’t. Here is what I found:

In my functions.php (not working) I had this line in a function but in fact it isn’t needed for this site.

$t = get_post_type( get_the_ID() );

I also saw in the function not working this difference. echo urlencode( $title ); as opposed to just echo $title.

And here is the strange bit. I then took the good functions.php file and put these two things back in, emptied W3 total cache and the scan ran normally when it shouldn’t run. I have since removed them anyway and the malware scan runs.

Who knows why this prevented signatures from being loaded.

Interesting. So I suspect the caching plugin does something that breaks the process loading the signatures. With a default installation of W3 total cache, I can’t reproduce the issue.
I will think about it.