Resolve Invalid Proof Signature

Scenario/Problem: You discover that WOPI functionality is not functioning and find “Invalid Proof Signature” messages within the SharePoint logs.

Solution: Use the Update-SPWOPIProofKey cmdlet with the WOPI server name.

WOPI uses a public key to for communication between the SharePoint farm and the Office Web Apps server. Sometimes keys become unsynchronized and need to be reset. Use the Update-SPWOPIProofKey cmdlet with the optional -ServerName parameter to update the public key and resolve any invalid proof signature issues. Listing 26.8 shows an example.

Listing 26.8. Updating the WOPI Public Key

Update-SPWOPIProofKey -ServerName "Office.mycompany.com"

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