Runtime Error 457, "This key is already associated with an element of this collection," occurs when you're working with a Data collection in BUSY Software, you're attempting to add an element using a key that is already in use within that collection. In other words, each key in a collection must be unique.
To resolve Runtime Error 457, you should ensure that you're using distinct keys for each element you add to the collection. Here are some steps to address this error:
Step 1. : Clear all pending synchronisation data in the queue including Head office and branch office.
Step 2: After completing step 1, retry the same process. This action may resolve the issue.