We return error message 429 when you've exceeded your rate limits for API calls. If you execute more than 6 requests per second for a sustained period - then our service begins to reject your requests with Http status code 429.  

This most commonly occurs when a user attempts to apply permissions recursively to a very large set of folders. Our Web App attempts to throttle your requests transparently in order to stay under our API limits but it can not account for other concurrent activity such as additional connections and requests originating from FTP clients, FolderSync clients, etc...

If you are attempting to execute a large number of requests (you have a very large set of nested folders) then you can avoid Error 429 by:

• If possible, first stop any other clients or interface connections that are running in parallel.
• Divide your operation into a few separate recursive operations by applying recursive permission changes in smaller batches at a deeper level.