Can someone please help me with a one word substitute for something (an event probably) that happens only under very specific (and strict) circumstance?
So, my firm is a software vendor. There is this client who uses this software. They faced an error when they used the software in a very specific way. Or when they specifically followed a set of actions in a certain sequence. Now, they are afraid that they might encounter this error on a regular basis.
What I want to convey to them is:
This was a/an _______ error. Which you encountered because you specifically chose to use the software the way that you did in this particular instance. In future you will only get it if you again follow the same set of actions in the same order.