The phrase "a crass error" is correct and usable in written English.
It can be used to describe a mistake that is considered rude, insensitive, or lacking in refinement.
Example: "The report contained a crass error that offended many readers and undermined the author's credibility."
Alternatives: "a blatant mistake" or "a gross error".
Sir Larry Lamb, a personal friend of Thatcher and then Daily Express editor, declared in 1985 that Mandela's unconditional release would be "a crass error".
Mikel John Obi, the defensive midfielder, was guilty of a crass error in letting himself be dispossessed deep in his own half by Adam.
He has had his moments this season, particularly at Spa, where he ran Hamilton off the road in a crass error of judgement, but yesterday he recovered any lingering PR deficit.
July 21 Mandelson criticises BBC and Gilligan Speaking on the BBC Radio 4 Today programme, Mr Mandelson criticises Andrew Gilligan, describing him as a "loose cannon" and says BBC governors made a "crass error" in backing him to the hilt.
In Cardiff, for example, it was a crass error that England's best bowler, Swann, did not bowl his full complement of overs and the novel notion of attempting to bowl a succession of yorkers wide of off stump at the end of the innings looked too clever by half.
If so, it was a crass mistake.
Though he spoke warmly about the benefits of eliminating the double taxation of dividends, a centrepiece of the plan, Mr Greenspan made the crass error of suggesting that tax cuts needed to be paid for and that budget deficits matter.
Hitchens makes "the same crass error... Christianity was never meant to be an explanation of anything... It's rather like saying that thanks to the electric toaster we can forget about Chekhov".
Crass error, right on half-time.
O'Grady went on to claim there was no cosiness in the Tour's response to Garcia's crass error or attitude to race and participation in golf.
