Hi everyone. I'm looking at our Auth0 logs for failed logins and I'm hitting a wall. The logs show the username/email used in the attempt, but the `user_id` field is always null for these events. I need to link these failed attempts to specific user accounts in our Salesforce CRM for the security team.
Is this normal behavior? How do you all track which account is being targeted when a login fails? I'm worried I'm missing a configuration step or a log setting. Any pointers on how to debug this would be really helpful.
Yeah, that's actually expected behavior from Auth0. If the login fails, there's no authenticated user session yet, so there's no user_id to populate. It's a bit of a blind spot.
What we ended up doing was enriching the raw log event *after* it landed in our pipeline. We'd parse the username/email from the log and do a lookup against our user directory (a small, cached dataset in our streaming app). That appended the internal user_id before the events went to our security data store.
Could you pipe your Auth0 logs into a stream processor and join them with a user table? That's the usual workaround.
Yes, that's completely normal, and it's a common source of frustration when you first run into it. The user_id is a property of the authenticated user session, so like user712 said, it doesn't exist yet on a failure.
For debugging, I'd start by confirming your log streaming is capturing the right event type. Check that you're looking at the `f` (failed) log events, specifically `f` for login failures. The `username` field there is your key.
A practical next step before building a stream processor could be to write a small script that periodically fetches these failure logs, extracts the usernames, and matches them against a recent user export from your CRM. It's a manual join, but it proves the data flow and buys you time to design the enrichment pipeline.
ship early, test often
I agree that verifying the `f` event type is the correct starting point. However, the manual script approach for periodic joins introduces a latency problem for the security team's use case. They're likely operating on a need-to-know basis in near-real-time, not with batch exports from yesterday.
If you proceed with the script, measure the end-to-end lag from failed login to CRM update. You'll probably find it's measured in hours, not seconds. This is where a stream processor, as user712 mentioned, becomes non-negotiable. The temporary script should explicitly be a prototype to validate the lookup logic and data shape, not a long-term solution. Its performance characteristics will be wholly different from a production enrichment pipeline.
--perf
Yeah, it's normal, and it's a feature, not a bug. Auth0 can't populate a `user_id` for an identity it hasn't confirmed yet. You're not missing a log setting.
Your real question is about the join path. The `username` field in the failure event is the key, but you need to resolve it to your internal ID. That lookup can happen in a few places, each with different complexity:
* In a post-login rule (if you can derive the internal ID from the user's profile pre-CRM). This adds latency to the auth flow itself.
* In a stream processor after the log is emitted (as user712 mentioned). This keeps auth fast and is my usual pick.
* As a batch job later. This is simpler to set up but means your security team is always looking at stale data.
Before you build anything, trace where that internal `user_id` actually lives in your system. Is it in Auth0's app metadata? In a separate DB? That determines your enrichment strategy.
Ah, welcome to one of the most classic Auth0 "gotchas" 😅 It absolutely feels like you're missing something, but you're not. The null `user_id` on failures is completely normal, and it trips up almost everyone the first time they need to tie security events back to a CRM record.
The real trick isn't in the logs themselves, it's in that join between the attempted username and your Salesforce User object. I've been down this exact path with both HubSpot and Salesforce. Your security team is going to want that internal ID, so you need to build the bridge.
Before you over-engineer a stream processor, do a quick-and-dirty test: pull the last 100 failure logs and write a simple script that takes the usernames and matches them against a report of active users from Salesforce (using the Email field). That'll confirm the data is there and force you to think about edge cases, like what happens when a user changes their email in your CRM but the attacker is using an old one.