Unable to compare _bpchar for similarity in WHERE-clause (MINOR A NNOYANCE)

When I try to write an UPDATE where I include a WHERE-clause like:
[WHERE something='{"a","b","c"}], where something is a character[], i get
the errormessage:[Unable to identify an operator = for types '_bpchar and
'unknown' You will have to retype this query using an explicit cast]

The above statement works for text[]. Can you please provide an explanation
or if it just my query that is wrong, I would be happy.
                            Best regards,
                                  Nicolai Hansen

PS! I couldn't fill out your online form