Random Internal Server Error while sending PM's or Posting

[Xanth18]

This is a shot in the dark, as this error we're getting is completely random and I cannot seem to duplicate it.

One of my users reported getting this error while trying to send a PM to another user:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at [email protected] to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log.

I, myself, have received this as well completely random while submitting a post - usually a long one, I've noticed.

Here are the mods I have installed:

Pretty URLs
Stop Forum Spam
Giphy
Google Analytics Code
Pretty URLs Extra

As I said, since this is a random occurrence I feel like asking this is a shot in the dark, but figured I'd try anyway.

Thanks in advance!

[Kindred]

You would need to look at your server error logs (not smf logs)

Your server should document any of these errors there