Error
message
Could not hoist data into experiment.subject_id for event event of schema at /analytics/product_metrics/web/base/2.0.0 destined to stream mediawiki.product_metrics.contributors.experiments: x-experiment-enrollments header does not have a matching enrollment in event data: One of 'experiment.enrolled' or 'experiment.assigned' fields does not have matching experiment or group name in header.
event
{
"instrument_name": "ClickThroughRateInstrument",
"funnel_entry_token": "redacted",
"element_friendly_name": "Sign up",
"experiment": {
"enrolled": "growthexperiments-editattempt-anonwarning",
"assigned": "control",
"subject_id": "awaiting",
"sampling_unit": "edge-unique",
"coordinator": "default"
},
"$schema": "/analytics/product_metrics/web/base/2.0.0",
"meta": {
"domain": "ru.wikipedia.org",
"stream": "mediawiki.product_metrics.contributors.experiments",
"id": "4f2e6558-710c-44fb-b24e-84d96c8daad0",
"dt": "2026-03-24T15:32:59.787Z",
"request_id": "02a675d7-0116-4c51-8266-c7502abdef2f"
},
"dt": "2026-03-24T15:32:55.426Z",
"action": "impression",
"agent": {
"client_platform": "mediawiki_js",
"client_platform_family": "mobile_browser"
},
"performer": {
"is_logged_in": false,
"is_bot": false,
"pageview_id": "redacted",
"active_browsing_session_token": "redacted",
"id": 0
},
"mediawiki": {
"skin": "minerva",
"database": "ruwiki"
}
}Impact
55 events in the last 24h. Data for this users is not being collected for the experiment
Notes
This is only happening in wikis where growthexperiments-editattempt-anonwarning experiment is running. See the "subject_id": "awaiting", for some reason eventgate-wikimedia did not find the experiment in eventgate-wikimedia.js#L666.