Hopeless with error Incorrect or out of date login key in Domain Mapping

Dear Wpmudev,

I’ve installed Domain Mapping recently. It was a perfect solution for multisite with multi-domains. But “Incorrect or out of date login key” error has been happening frequently recently.

I’ve made a small research on this site and tried to remove all cookies or force user login with mapped domain but the error still shows to some users.

Any guy has a better solution for this?