Welcome to LQ!
Please provide the exact error message, copy and paste it if this is possible.
I tried doing a websearch on:
"clipboard format not found"
"clipboard format is not found"
"required clipboard format"
"required clipboard format not fuound"
and got no matches to this problem. This probably means that you have not copied it exactly. Exact error messages make identifying the problem much easier.
Also does this happen every time, or was it just once? Does it happen on every webpage? What happens if you use another browser?