DynamoDB - Key element does not match the schema

For others who have faced the same challenge and the issue is not fixed by above answers, it is always better to double check the data type of the value being updated, in my case the primary key was expecting a Number and I was trying to update with a string. Silly me

You are only providing half of your primary key. Your primary key is a combination of the partition key and range key. You need to include the range key in your Key attribute in the update parameters.