Understanding Failure Description: $anon_distinct_id Mismatch Issue

Juan I.

what does it mean this when I identify a user: Failure Description $anon_distinct_id didn't match expected GUID

2 comments

kapa.ai
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Hi Juan I., Please stand by as I search the Mixpanel knowledge base for an AI-powered answer. I normally take about 15 seconds or so. In case AI cannot answer your question, feel free to reach out to Mixpanel support at mixpanel.com/get-support. If you have follow-up questions for this thread, please tag me again with your question: @kapa.ai <follow-up question> 👋
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kapa.ai
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This error message appears when you're trying to use Mixpanel's Original ID Merge system and the $identify event fails because the anonymous ID you provided doesn't match the expected format.In Mixpanel's Original ID Merge system, the $identify event is used to link an anonymous ID with a user ID. However, there's a specific requirement: the $anon_id must be in UUID v4 format (a specific type of globally unique identifier) and must not have been previously merged with another ID.As the error message indicates, the anonymous ID you're trying to use doesn't match the expected GUID (Globally Unique Identifier) format, which is why the identification is failing.Here's what you can do to fix this: 1. Make sure the anonymous ID you're passing is in UUID v4 format 2. Check that you're not trying to merge an ID that was already merged with another IDThis is specifically relevant to Mixpanel's Original ID Merge system. If you're using the Simplified ID Merge system, the approach would be different.Identifying Users (Original) explains that the $identify event "will only merge an $anon_id that is in UUIDv4 format (anonymous ID format generated by Mixpanel and Segment) and only if the $anon_id was not previously merged to another $identified_id."If you're implementing server-side tracking, you might need to generate UUIDs yourself for anonymous users before attempting to identify them.
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Understanding Failure Description: $anon_distinct_id Mismatch Issue | Mixpanel Community