Word for making a basic mistake in your field of expertise? [closed]

For example, a computer security expert can be an expert and making a basic mistake, perhaps unrelated to his personality but highly relevant to his field of expertise and a mistake that just about anybody could do but just because he is a security expert he especially should not have done it.

I don't mean stupid mistake or stupid error but I mean contradictory and almost similar to a double-standard.

Jeff teaches English but he couldn't spell "occurrence".

Or for example

George is a professional Microsoft Windows programmer but he doesn't know what alt+tab does.

Or

Henry is a surgeon but he cut himself shaving.

I don't necessarily mean something like a police officer who himself is corrupt or a judge who is corrupt because those are not accidents or mistakes but deliberate.

Albert Einstein was a genius but couldn't remember his own address and entered the wrong house when going home.

(Perhaps the above Einstein example is not a great example because scientist could be absent-minded.)

I mean more like actually mistakenly missing the basics of your own speciality or making a human error that anybody else could do except you because you are supposed to be the specialist.

I think the classic example could be Bill Gates trying to show how good Microsoft Windows is and it crashes.

Or a news anchor, who should be a specialist in not making a word mistake, actually makes a word mistake.

Or a judge or an attorney, who should be experts in law and rights, wouldn't know something trivial about law and right e.g. unknowingly about that blackmailing is a crime.

I almost made such a mistake myself. I was an IT specialist and computer technician at a client's office and their boss was teaching himself the basics of programming and asking me about something basic. I actually got it right but I was not completely certain about something basic while actually being able to solve complicated and advanced problems for them.


Such mistakes are bloopers.

ODO:

blooper NOUN
North American informal
1 An embarrassing error

‘Home cooks perhaps identified with Mrs. Child, who, though she clearly knew her sauces and soufflés, also committed bloopers on camera.’


Not a single word, but one could call this a rookie mistake.

An example is "Trump's Trade Chief Makes a Rookie Mistake".

The Cato Institute’s Dan Ikenson recently took Navarro to task for his views on trade. Ikenson says Navarro is making an elementary error when he writes:

When net exports are negative, that is, when a country runs a trade deficit by importing more than it exports, this subtracts from growth.

It’s definitely not true that trade deficits always subtract from growth.


Consider "lapse", which is defined by oxforddictionaries.com as

A brief or temporary failure of concentration, memory, or judgement

This perhaps applies best to the "surgeon who cuts himself shaving" example. For the other two examples, in which the expert lacks one piece of basic knowledge in his or her chosen field, consider "blind spot", this sense of which is defined by oxforddictionaries.com as

An area in which a person lacks understanding [...]


Blunder.

A careless or stupid mistake.


I like a lot of the answers here, but thought I'd throw yet another one into the mix:

flub

  1. to perform poorly; blunder; bungle:

He flubbed the last shot and lost the match.

(Quote from Dictionary.com)

(Mostly I just like saying the word...)