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ERROR - Exception reading manifest from file Exception reading manifest from file:///C/Program%20Files/ANSYS% 20inc/v251/optiSLang/lib/optiSLangExcelAddln.vsto:
Authored by Caleb Scharf
March 10th, 2025
914 views
10 likes
KB3087544
ERROR
Every time excel is opened the follow error occurs.

Installing Office customization
There was an error during installation.
Name:
From: file:///C:/Program Files/ANSYS
lnc/v251/optiSLang/lib/optiSLangExcelAddln.vsto
Exception reading manifest from file:///C/Program%20Files/ANSYS%
20inc/v251/optiSLang/lib/optiSLangExcelAddln.vsto: the manifest may not be valid
or the file could not be opened.
Name:
From: file:///C:/Program Files/ANSYS lnc/v251/optiSLang/lib/optiSLangExcelAddln.vsto
************** Exception Text **************
System.Deployment.Application.InvalidDeploymentException: Exception reading manifest from file:///C:/Program%20Files/ANSYS%
20inc/v251/optiSLang/lib/optiSLangExcelAddln.vsto: the manifest may not be valid or the file could not be opened. — >
System.Deployment.Application.InvalidDeploymentException: Manifest XML signature is not valid. ---> System.Security.Cryptography.CryptographicException: The form specified for the subject is not one supported or known by the specified trust provider.
at
System.Deployment.lnternal.CodeSigning.SignedCmiManifest.Verify(CmiManifestVerify
Flags verifyFlags)
at
System.Deployment.Application.Manifest.AssemblyManifest.ValidateSignature(Stream s)
--- End of inner exception stack trace ---
Software & Version
***OptiSLang 2025R1***
*This example was taken from this version but is not necessarily limited to this version.
Description/Cause
This occurred after installing Optislang 2025.
This is because the optiSLang excel add in is not available in 2025. Its a known issue and will likely be fixed in a service pack.
Solution
- Open Excel > File > Options > follow the picture below.
- You may need to open excel as an Administrator by Right clicking and selecting Run as Administrator.
- You may need to open excel as an Administrator by Right clicking and selecting Run as Administrator.
