Searching by _tag with system-only (no value) produces errors on HAPI JPA Server

25 views

Skip to first unread message

Andrea Caloni

unread,

Apr 13, 2026, 5:38:06 AM (7 days ago) Apr 13

to HAPI FHIR

Hi,

I'm using HAPI FHIR Server (JPA) and I'm trying to search for all QuestionnaireResponse resources that have a _tag with a specific system (http://myCompany.com/CodeSystem/Questionario) and any value.
According to the FHIR R4 specification for token search parameters, the syntax [parameter]=[system]| (with a trailing pipe and no value) should match any resource tagged with that system, regardless of the code/value.

My search request looks like this:

GET [base]/QuestionnaireResponse?_tag=http://myCompany.com/CodeSystem/Questionario|

However, this query produce the following error:

"HAPI-1218: Missing _tag parameter (must supply a value/code and not just a system): http://myCompany.com/CodeSystem/Questionario|"

even though I have QuestionnaireResponse resources that do carry tags with that system (and various values).

If I specify the full system|value pair explicitly, the search works correctly.

Is the system-only token search syntax (system| with trailing pipe) supported by HAPI FHIR for the _tag parameter?
If not, is this a known limitation or a bug?

Environment:
• HAPI FHIR Server (JPA) — 8.8.0
• FHIR R4
• Client: Firely .NET SDK (Hl7.Fhir.R4)

Thank you