I got the following error:
A database query error has occurred. This may indicate a bug in the software. Function: LinkSearchPage::reallyDoQuery Error: 2013 Lost connection to MySQL server during query (10.64.32.21)
when I tried to use Special:LinkSearch with an offset of 100,000.
Reproducible anytime (example)
Admittedly, this is an edge case, but it'd be nice to get something other than a database error message :)
Yes, I just checked and it seems that if you open the page again a while after you get the error message, it works. This was reproducible for three different searches when I submitted this, and I just tested again with another URL.
I suspect there is a timeout somewhere, but the query continues to run despite the timeout, which means that once it completes, it's in cache and you can access it. You only get the error the first time you do the query.
The problem also occasionally appears at lower offsets. I just did three queries with an offset of 50,000, and two of them worked, but the third one gave the same error.