The phrase "a common myth" is correct and usable in written English.
It can be used when referring to a widely held but false belief or idea.
Example: "Many people believe that bats are blind, but this is a common myth."
Alternatives: "a widespread misconception" or "a prevalent fallacy".
A common myth about electromagnetic waves is that they bounce off one another if they meet.
There's a common myth that Burning Man works on a bartering system.
It's a common myth that pizza boxes aren't recyclable, for example, Carpenter says.
A. "It's a common myth that injuries can cause cancer," the American Cancer Society says on its Web site.
First, such calls to "regain" control of the border suffer from historical amnesia, perpetuating a common myth that it was ever actually under control.
There is a common myth that actors are all extroverts, but many of the best are rather shy and not especially articulate.
His letter added: "There is a common myth that there is overwhelming opposition to crop biotechnology and food derived from it in this country..
This is a common myth, and while charities do enjoy some tax and VAT reliefs, they are also liable for a number of tax and VAT charges.
Graduate programmes are dominated by men and it's a common myth that this is because male candidates are better at making it through the selection process.
A common myth about Addams is that because the fictional world of his cartoons was regularly inhabited by people and creatures who resembled sociopaths, he in some way shared these characteristics.
This is also the reason why feminism is not struggling to simply reverse the present power relationship and put women in charge instead of men (though this is a common myth about feminist politics).
