Map<String, Object> in AuraEnabled now failing in Spring 19 with "Value provided is invalid for action parameter"
Fix for this issue(W-5724071) is in the upcoming patch (scheduled to be released in mid Jan).
In Spring'19 salesforce is addressing various long standing issues with deserialization pertaining to apex actions. Brief list of enhancements include,
- Make conversion of all primitive apex data types work for positive use cases. There were a few reported issues here by the community (e.g. link).
- Make incorrect usage error out with a clear develop error. Currently any incorrect usage results in internal server error (resulting in noise for us and useless stack-id for developer)
- Add support POJO style user defined Apex types
- Make handing of SObjects consistent
- Add support for nested lists/maps
I have also reached out to documentation team to ensure more details of the enhancements get incorporated in the public docs.