Excel VSTO add-ins being blocked from starting

Brett Holmes 21 Reputation points


For some reason this won't post unless I add tags, and the tags that come up aren't really related - so apologies for posing in the wrong area!

I have a number of VSTO add-ins that will no longer load after a recent update due to a ClickOnceAddInTrustEvaluator error. This is new as of the recent update which installed this morning.

I don't have a proper security certificate and don't have any desire to purchase one as the add-ins are only used by me, but it won't even run off a Test Certificate in debug mode.

Error message as follows:

************** Exception Text **************
System.Security.SecurityException: Customized functionality in this application will not work because the certificate used to sign the deployment manifest for <snip> or its location is not trusted. Contact your administrator for further assistance.
at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInTrustEvaluator.VerifyTrustPromptKeyInternal(ClickOnceTrustPromptKeyValue promptKeyValue, DeploymentSignatureInformation signatureInformation, String productName, TrustStatus status)
at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInTrustEvaluator.VerifyTrustUsingPromptKey(Uri manifest, DeploymentSignatureInformation signatureInformation, String productName, TrustStatus status)
at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.ProcessSHA2Manifest(ActivationContext context, DeploymentSignatureInformation signatureInformation, PermissionSet permissionsRequested, Uri manifest, ManifestSignatureInformationCollection signatures, AddInInstallationStatus installState, TrustStatus sha256TrustStatus, X509Certificate2 sha256PublisherCert)
at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.VerifySecurity(ActivationContext context, Uri manifest, AddInInstallationStatus installState)
at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.InstallAddIn()
The Zone of the assembly that failed was:

Not Monitored
Not Monitored
Tag not monitored by Microsoft.
37,537 questions
0 comments No comments
{count} votes

Accepted answer
  1. Anonymous

    Excel and VSTO are not currently supported here on QnA. They're actively answering question in dedicated forums here.



    --please don't forget to Accept as answer if the reply is helpful--

    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    0 comments No comments

1 additional answer

Sort by: Most helpful
  1. Brett Holmes 21 Reputation points

    Thanks. Reposted in the correct location.

    0 comments No comments