GTPv2 cause 77 Syntactic errors in packet filter(s)
GTPv2-C cause3GPP TS 29.274 §8.4 (Table 8.4-1)
What it means
One of the packet filters in the request had a syntax error.
Where you see it
In the Cause IE of a GTPv2-C response (Create Session, Modify Bearer, Delete Session…) on S11, S5 or S8.
What to check
Check the exact packet filter contents in the request.
Check which node sent the response (MME, SGW or PGW): the cause belongs to that node's decision.
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