Error occurs when job service is running behind load balancer

All application servers need to use the same session certificate. Have you ensured they do?

session certificates were different and now I have modified it and bot app server has same session certificate. But on one of the app servers, I am getting error 

2019-01-07 07:13:40.5679 ERROR (ObjectLog ) : [System.Security.Cryptography.CryptographicException] Key not valid for use in specified state.

System.Security.Cryptography.CryptographicException: Key not valid for use in specified state.

Sounds like the application server throwing the error does not have access to the private key of the certificate.

Process I followed is

1. Installed app server on server1 and created new session token certificate here

2. Exported this certificate with private key

3. Imported this cert on server2 and used this same session token certificate while installing app server on server2

What am I missing here?

It was just an idea. But did you check that the certificate is installed in the same store on both machines? Did you check the ACLs on the private key for the certificate?

Certificate is stored in same store on both the machines and I have given "Full Control" to IIS App pool and even to Everyone. Still I am getting same error

Okay. One thing that might be the case.

When you import the certificate, you need to mark the certificate as exportable.

So you need to delete it first and then import it again with the exportable option set.

Hi, I have imported the certificate again as you said and app servers are working as expected now. But I am still getting same error in job service logs. 

Does your load balancer use sticky sessions?

yes it uses sticky sessions