Hmmm... I'm not sure where that would be coming from.  I try to be more descriptive/user-friendly in the odd cases where I come across an input error, but I may have missed something.

If you're getting the error message on bitMerlin and want to send me a screenshot of what you're seeing to support@bitmerl.in I'll gladly take a look.

If you're getting it from another faucet that we're linked to in the rotator, it could be a problem on the faucet's end.  If you give me the name of the faucet (should be visible right in our rotator) or the URL I can try it on my end and at least figure out if the issue is on the faucet's end or not.