Open maildatabase returns an error: Unable to load saved action; action is corrupt

When i open the maildatabase of the user in question, i get the following error message:

Can someone help me on this one?

actions so far:

replace design withn inotes6.ntf

replace design back to mail85.ntf

deleted all design elements

l convert -u mail\wlande.nsf * mail85.ntf

All above wasn’t the solution.