PL/SQL Developer 11.0.4.1774, and PL/SQL Developer 12.0.4.1826
oracle rdbms 11.2.0.4 RAC and standalone

We recently migrated from stand-alone Oracle instances to RAC instances. A procedure will run fine in debugger mode within a standalone database instance, while the same procedure in a RAC instance with the same data cannot get past the "start debugger" without hanging, in other words we never get to the point to even step into the code.

Let me know if there is any other information I can provide.

The Oracle Debug API (sys.dbms_debug) internally uses dbms_pipe messages to communicate between the controlling session and the debug session, which apparently can fail on RAC systems. The only workaround is to modify the tnsnames.ora file to connect to only 1 node of the cluster without load balancing and failover.

I have verified this has fixed the debugger issue with RAC (failover) connection strings. Forced my tns connection to one node and debugger no longer hangs. Thanks! --Kate.