How to fix Error message: The signature applied to this document is invalid. Please clear it and sign again.

Hi, I tried to find exact solution but nothing seems very helpful.. although i have found a guide and a thread related to your problem.. May be it will be helpful for you.

Validating digital signatures, Adobe Acrobat and Signature valid or invalid

Thanks

Did you apply this signature? If so, right-click it and select Clear Signature, and then apply it again.

If not there's not much you can do about it.