Can any one find this Solution for this problem.?
Can you check if DB link works correctly? Please run simple check of: desc user_tables@dev01cdb.
I received the same errors you described when attempting to hot clone an unencrypted PDB between two exadata machines (create pluggable database xyz_clone from xyz@db_link;) after re-imaging the target machine. In my case we failed to recreate the sqlnet.ora file. The copy worked after creating the sqlnet file on the target machine in the TNS_ADMIN path like this:
YMMV, but hope this helps. (Credit to my coworker who discovered the problem.)
I think the relevant "tns" entries were not added in ALL the nodes "tnsnames.ora" file in your environment. So, check "tnsnames.ora" on ALL the Cluster nodes,
then add the relevant '<tnsname entry>' in "tnsnames.ora" file on ALL the Cluster nodes.