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Scope
How to fix the Salesforce error - Locale not in allowed values?
Summary
This error occurs when the customer is created with an invalid locale in Salesforce.
Solution
In order to fix this error, you would need to navigate to the contact level & in the language field for example if you have passed Dutch, you would please pass the language as just the code, for dutch language the code is nl, fill in the language field as nl & then try to create the customer.
Basically, instead of passing the languages, we need to pass the codes, for example, instead of English it would be en
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