Hi, I've seen this question often but it wasn't simillar with my problem.
So i receive this error on frontend after i modify a color for an element in a css file.
After i clear the cache for a several time the site came back and it was ok.
Afer a few hours the same thing happend. And i did the same step to clear cache and the site was working properly.
I searched for the file log with the error number in var/report but that number it wasn't there.
I mention that my site worked fine the other days.
So , what cause this error ?