PDS search failing Invalid value - '' in header 'NHSD-Session-URID

When attempting to perform a participant search we are occasionally receiving an error response with the following detail

Invalid value - ‘’ in header ‘NHSD-Session-URID’

I was under the impression this was an optional field.

For info we are operating in Health care worker access mode - using smarcard and yubi authentication.

The ‘NHSD-Session-URID’ header is indeed optional, but if it is present it must be valid.

It looks like, in this case, you’re including the header with an empty value, which is Invalid

Interesting as far I as I can tell from the code this header is not set when the api call is made.