3382727 - Error message: "Please correct the language. ABC isn't valid." on web service message monitoring

Error message: "Please correct the language. ABC isn't valid." on web service message monitoring

SAP Cloud for Customer

In C4C, 

1. go to Administrator work center
2. go to General Settings facet
3. go to Web Service Message Monitoring
4. search for the Message ID: XXXXXXXXXXXXXXXXXXXXXXXXX
5. check for the Error message: "Please correct the language. ABC isn't valid."

Customer did not enable the necessary languages in Business Configuration

Customer must enable the necessary languages as Additional Communication Languages in Business Configuration > Overview > Additional Communication Languages.

Just a reminder: Language code does not have code list mapping support due to technical limitation ( SAP stores the language key internally as a single character for the reason of memory optimization and ISO codes(2 digit) is used for communication)
C4C strictly follows ISO codes for language codes and the option for code list mappings is not available, hence, whatever values are sent in the payload are considered directly. And since the system strictly follows ISO codes, this is why there is not an option to create new language codes in C4C.
So you have to use the languages supported (Those available under Additional Communication Languages in Business Configuration). 

2653429 - How to Define Additional Communication Languages

language, additional communication language, scoping, business configuration, Additional Communication Languages , KBA , LOD-CRM-INT-ERP , Integration of C4C with ERP , LOD-CRM-INT-S4H , Integration of C4C with S/4 HANA , Problem