EMM cause (LTE NAS)3GPP TS 24.301 §9.9.3.9 and Annex A
What it means
ESM failure: the attach failed because the bundled PDN connectivity request failed. The real reason is in the ESM cause of the same message.
Where you see it
In LTE NAS Attach reject, Tracking area update reject, Service reject or Detach request.
What to check
Look at the ESM cause next to it (e.g. #27 unknown APN, #33 not subscribed).
Look at the S6a (MME↔HSS) and S11 messages just before the reject: they usually show the real trigger.
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