Since upgrading a load balanced Umbraco instance with 1 publisher and 2 subscribers from 13.1.1 to 13.2.2 we are getting continuous log warnings stating:

"Error unprotecting the session cookie. System.Security.Cryptography.CryptographicException: The key {SOME-GUID-HERE} was not found in the key ring.

I have applied the sql-based data protection api as documented here in an attempt to mitigate the issue: https://learn.microsoft.com/en-gb/aspnet/core/security/data-protection/configuration/overview?view=aspnetcore-8.0#persistkeystodbcontext to our test instance and can see the values being written to the database, but its had no effect on the cookie warnings. Up until now we have had no data protection configured, so it has used the default file system keys.

The same warnings are being logged continuously regardless of whether data protection is configured or not, with no site visitors. I have tried clearing cookies.

This site was originally a v9 site that was migrated up to v13.1.1. It has been running fine up until last week when we upgraded it to v13.2.2.

Hosted in Azure.

Anyone able to help shed some light on what is going on?