Mutaul Auth Error - Peer cert verify error: unable to get local issuer certificate

Hi, We have implemented a Mutual authentication for one of our client. The client has been provided the cert from their side which we have added under Advertised Certificate Authorities and an intermediate bundle at Trusted Certificate Authorities. However they are not able to connect with us with the set up.

 

When I have checked the logs on F5 ,following error has been observed.

 

Peer cert verify error: unable to get local issuer certificate (depth .....)

 

Any inputs of how this can be fixed will be of great help.