I am having a cockpit problem with this TLM error:
I have class A with a port
uvm_port_put #(base_txn) pp;
I have class B with an export
uvm_put_export #(base_txn) pexp;
I have class C that instantiates A and B and makes the connection in connect()
A.pp.connect(B.pexp);
I can not get this to run and get the above error during runtime.
Is there a tool to debug TLM connection problems?

This warning indicates that the port has not been connected to anything.
Did you remember to construct the export?
If you can share some code it will be easier to see what the problem might be.