“You do not have sufficient permissions to access this page”

Why is this happening?

I already installed User role editor and clicked on “reset”, but the above message still appears.

How to fix it?

Thank you.

[@netweb Keymaster 10 years, 12 months ago]

The ‘User Role Editor’ will not fix this issue, it has nothing to do with bbPress and will probably hinder your troubleshoot rather than helping.

Have you tried running the ‘Remap existing users to default forum roles’ repair tool?
https://codex.bbpress.org/repair-forums/