Error 0x80091005 when signing msix

Copper Contributor



I'm trying to sign an msix file I've created, however the signtool keeps giving me an error:

SignTool Error: An unexpected internal error has occurred.
Error information: "Error: SignerSign() failed." (-2146889723/0x80091005)


The publishername of the msix matches the subjectname of my certificate.

I cannot find any entries in eventlog:

PS C:\Users\Robin> Get-WinEvent -ProviderName "Microsoft-Windows-AppxPackagingOM"

ProviderName: Microsoft-Windows-AppxPackagingOM

TimeCreated Id LevelDisplayName Message
----------- -- ---------------- -------
1/14/2021 3:28:34 PM 181 Information The reader was created successfully without manifest validation.


Enhanced Key Usage string: Code Signing (


Signing .msi, .exe, .ps1 works fine with the certificate.


Can anyone help me with this? Is something wrong with the certificate, or am I doing something wrong in the msix?



2 Replies

Hi @RobinRamaekers 


From what I know under Event viewer you can only find logs regarding your MSIX installation/uninstallation - not the build process.


Back to signing. These errors are the hardest to pinpoint and signtool does not help at all.

Try to extract (with 7-zip) the contents of MSIX package and sign the files directly (update the script to recursively sign each file from the extracted folder). If this works, at least you can exclude a common error where the MSIX contains invalid PE files. Usually, this should give a different error code from Signtool, but...

Optionally, try to build another MSIX package to see if the problem is manifesting for any package or just this one.


@Bogdan Mitrache I was able to sign. Looks like I was using the 32-bit signtool.exe, when I switched over to the 64-bit it seemed to work.