find-scu failed with unknown transfer syntax

I’m not sure if this a bug, incorrect usage or just bad behavior of the PACS. On querying a Siemens PACS, pynetdicom3 raised an exception in add_transfer_syntax because of one of the transfer syntaxes having the value ‘unknown’. As far as I could see, this came from the PACS, though I may have missed something that generated it on the pynetdicom side. If ignoring ‘unknown’ transfer syntaxes, all works fine. Regardless of the source of the problem, I think it makes sense just to ignore invalid transfer syntaxes, maybe using some strict option that allows that if set to False. What do you think?

[moloney]

I ran into this issue myself with a Siemens MRI. It seems when the association request contains presentation contexts with abstract syntaxes the machine doesn’t know about (in my case the three “Composite Instance” ones), it fills out the UID as “unknown” when rejecting that context in the response.

I can confirm this just causes some warnings (three per association) but everything works fine.

[mrbean-bremen]

I currently don’t have access to the system where the problem occurred - I will test this again sometime later (or probably write a test for this). Anyway, your changes should certainly fix the problem, as now only a warning is issued instead of an exception raised, so I close this issue for now. Thanks for the excellent work!