Why "managable" stands outside the dictionary

What kind of error is it?

Spelling Error

Why do people make this mistake?

People might drop the "e" mistakenly, as it sounds correct when spoken and follows the typical English rule of dropping the "e" before adding certain suffixes, which might lead to confusion.

What is correct?

"Manageable" is the correct spelling of the word. It means something that can be managed, controlled, or handled.