Sitecore Experience Commerce - Identity Server No signing credential is configured

After upgrading Sitecore Identity Server as part of a migration from update 1 to update 2 of Experience Commerce, the following error appeared after attempting to authenticate in postman:

Unhandled exception: "System.InvalidOperationException: No signing credential is configured. Can't create JWT token
   at IdentityServer4.Services.DefaultTokenCreationService.<CreateHeaderAsync>d__5.MoveNext()

I was able to resolve this error by setting the correct thumbprint in the appsettings.json file of the identity server.