And got another complaint from a co-worker that the "Terminate" button "hangs" plsqldev.

Just got another complaint from a co-worker that lately Break is not working. Yes, we are using the same plsql dev version and same databases but still. Is there any way we could diagnose the prolem?

I'll jump into this conversation. I'm using PSD 14.0.4.1985. The About window says
OCI: version 12.1
DLL: c:\Oracle\instantclient_19_8\oci.dll
and I'm connected to an 11.2.0.4 DB
I'm using the 64 bit version of Instant Client
I have a query running and shortly after starting it, I clicked the red lightening bolt to break it and nothing happened. I've clicked it multiple times and nothing, also tried Session -> Break from the menu as well and nothing. PSD is still responsive, but the query continues to run. My Session Mode is "Multi session"

I used a Test window for the dbms_lock.sleep(seconds => 60); run against at 12.1 DB and it did not stop it. In fact, the Test window is still Executing.... and the time is up over 4 minutes now.

If I try to close the running tab and click Terminate, then that locks up PSD (which is probably to be expected).

I've successfully used Session Break before on prior versions of PSD against these two DBs when I was using the Instant Client 12.1. Is this a change in how Instant Client itself it working?

I re-pointed PSD back to the instantclient_12_1 I still had on my machine and ran the dbms_lock.sleep(20); test against the 12.1 DB. At 8 seconds, I pressed the red icon to break the session. At the 15 second mark, I I had the pop-up window appear that stated
ORA-01013: user requested cancel of current operation
ORA-06512: at "SYS.DBMS_LOCK", line 205
ORA-06512: at line 7

View program sources of error stack?

So it looks like PSD works correctly with Instant Client 12.1 for doing breaks, but not with Instant Client 19.8

I faced that problem recently. I put the line "DISABLE_OOB=on" in sqlnet.ora to overcome it. Don't ask me what Oracle changed and where it's documented: I don't know.

If you have MetaLink access, DISABLE_OOB is defined in Doc ID 373475.1 - What is DISABLE_OOB (Out Of Band Break)?

The short answer is it simply changes how the break is sent from client to server whether it is sent using urgent data provided by the underlying protocol. So it could be Oracle tweaked that underlying protocol handling in Instant Client 19c, but just a guess.

I know that, thanks. I meant I couldn't find the actual OCI change documented.

Yes, in my case the problem was - I was using Oracle client 19c against older (11g) databases.
Switching back to client version 12 helped.
Thanks guys for the hint!