Error validating access token

I am having the same problem as described here: https://www.ads-software.com/support/topic/access-token-session-invalidated/

The discussion was closed but never solved.

I re-authorized my account, I received the green successful authorization notice, but when I try a test post to FB, I get this:

”
Array ( [Warning] => [Error] => Error validating access token: The session has been invalidated because the user changed their password or Facebook has changed the session for security reasons. )
“

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