At first try to remove
/data/cache directory. If it won't help then go further.
It's a clue, that you've got such answer, because there are only several places in the system where such error report (with value dump) is returned, but you should check each one by one. I can't figure out what's wrong without access.
You should find all occurrences of string "
'Invalid request: '.print_r", then change each txt to some unique value, e.g. add 1, 2, 3, etc. In this way you'll find out which file causes the issue.