What does “Audit Failure” (a Windows Event) mean in the context of a Sitecore 9 “Could not create SSL/TLS secure channel” error?

Question

I have a Sitecore 9.1 XP local dev installation with self-signed certificates.

This is how the SSL Certificate for my Collection instance is configured:

<add name="xconnect.collection" connectionString="https://XPScaled910.collection" />
<add name="xconnect.collection.certificate" connectionString="StoreName=My;StoreLocation=LocalMachine;FindType=FindByThumbprint;FindValue=621B26950DC9DE426493B9698ECA36CDBD4CD26A" />

The XPScaled910.collection certificate is correctly configured in the PERSONAL store of the Local Computer, and the Application Pool identity of the Sitecore XP server has access to it (I edited the permissions):

When I run the xConnect Client Endpoint troubleshooter I get a Could not create SSL/TSL secure channel error and the following entry in the Windows Event Viewer:

But this does not tell me much about what steps to undertake next in order to resolve the error.

QUESTION

What does this Window Event ("Audit Failure") tells me? How can I overcome the

Answer 1

Can you please try below two fixes.

1. Check client certificate Thumbprint value in config file is maching with the certificate Thumbprint.

2. Give certificate access to app pool user.