How To Fix TPDA660 - The terminal ID &1 was set for outgoing requests.

SAP Error Message - Details

• Message type: E = Error

• Message class: TPDA - Debugger

• Message number: 660

• Message text: The terminal ID &1 was set for outgoing requests.

What causes this issue?

The terminal ID <(>&<)>1 was set for outgoing requests.
This terminal ID was set for the current external session (for the
current SAP GUI window).
All outgoing requests, e.g. RFC calls, then carry this terminal ID and
can pass it on in further requests. The debugger is activated if this
request then arrives in a system in which an external breakpoint, which
is also associated with this terminal ID, was set.
You can set a breakpoint and associate it with this terminal ID by
starting the SAP GUI window in which you set the breakpoint in the same
Windows logon.

Error message extract from SAP system. Copyright SAP SE.