I got an error when entering my account holder name for my bank account info when paying an invoice, asking to enter a valid first and last name of up to 50 characters. At first I thought it was objecting to my having 4 names, but eventually I realized that I'd included a space at the start of my name and removing it made the form accept my name.
But the validation error given was totally unhelpful for identifying what was wrong, which was 'Name may not begin with spaces.'