| Protocol | nas | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 24.501 | Spec Section | 8.2.4 |
| Direction | UE to AMF | Message Type | 5GMM signaling |
| Full message name | 5G NAS - Authentication Failure |
|---|---|
| Protocol | NAS |
| Technology | 5G |
| Direction | UE to AMF |
| Interface | N1 |
| Signaling bearer / channel | NAS signaling / Dedicated NAS message, commonly via UL Information Transfer |
| Typical trigger | Sent when the UE cannot validate the network's authentication challenge or encounters a challenge-related failure condition. |
| Main purpose | Lets the UE explicitly signal that authentication of the network failed or could not be completed. |
| Main specification | 3GPP TS 24.501, 8.2.4 |
| Release added | Release 15 |
| Procedures where used | 5G Initial Registration, 5G Authentication Procedure |
| Related timers | T3560 |
| Related cause values | 5GMM cause |
Authentication Failure is the UE's NAS message indicating that it could not validate or complete the network authentication challenge.
Lets the UE explicitly signal that authentication of the network failed or could not be completed.
Authentication Failure is the UE telling the network that it could not complete the authentication challenge successfully.
Call flow position: UE-side negative outcome within the authentication challenge-response exchange.
Typical state: UE could not successfully validate or use the received challenge.
Preconditions:
Next likely message: Authentication Reject or another network decision
Previous message(s): Authentication Request
Next message(s): Authentication Reject, New Authentication Request
Security context: Typically part of a failed authentication branch before full NAS security activation.
This message is not typically analyzed as ASN.1 on the wire. It is usually read as a NAS or protocol field structure instead.
Authentication Failure is a NAS 24.501 message, not an ASN.1 message.
Authentication Failure
Extended Protocol Discriminator: 5G Mobility Management
Security Header Type: Plain NAS
Message Type: Authentication Failure
5GMM Cause: MAC failure
| IE | Required | Description |
|---|---|---|
5GMM cause | Yes | Explains why the UE could not complete the authentication procedure. |
Authentication failure parameter | Optional | Optional failure detail, such as synchronization-related information. |
5GMM causeExplains why the UE could not complete the authentication procedure.
Presence: Required
In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.
Authentication failure parameterOptional failure detail, such as synchronization-related information.
Presence: Optional
In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.
Likely cause: The UE could not validate AUTN, detected MAC failure, or hit a synchronization-related problem.
What to inspect: Check the 5GMM cause, optional failure parameter, and the preceding challenge.
Next step: Troubleshoot subscriber credentials, synchronization context, and network authentication data.
It is the UE's message indicating that it could not validate or complete the network's authentication challenge.
Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.