Update PDP context response with error "Mandatory IE incorrect (201)"

The rate of error “Mandatory IE incorrect (201)” in our network has increased.
PGW answer the Update PDP context request with the above error.
Does anyone from the community know about the root cause ? or give explanation about the possible causes ?

Thanks for your support.

a received GTP signalling message Request, which has a valid length, a mandatory or a conditional extendable length TLV format information element may have a Length field value, which is different from the expected Length . In this case, if the Length field value is greater than expected, the extra unknown octets shall be discarded. if the Length field value is less than the number of fixed octets defined for that IE, preceding the extended field(s), the receiver shall try to continue the procedure, if possible. Otherwise, this information element shall be discarded, the error should be logged, and a Response shall be sent with Cause set to "Mandatory IE incorrect

May be you can check if some particular yes creating problem.

  • Change the first octet of the MSISDN IE to be 0 to indicate no extension as expected by the GGSN Node.