During backup and recovery operations, the following error may occur:
Problem Code 14021 - This code indicates that Microsoft was unable to respond to the volume of requests being made.
When Spanning Backup for Office 365 is attempting to process backup and recovery requests, through the Microsoft APIs, the successful completion of these tasks is impeded by multiple throttling responses from Microsoft:
HTTP status code 429 ("Too many requests")
This is an indication that your Office 365 service is being throttled by Microsoft. This throttling is not specific to just Spanning Backup for Office 365. This impacts any service that is running against an overly busy Office 365 instance and has been occurring for customers and ISVs who leverage Microsoft's APIs to access their Office 365 data.
For additional information, please review the following Microsoft Community discussion:
SharePoint 429 Error - Throttling - Microsoft Tech Community - 155067
What is the impact?
To ensure the greatest opportunity for successful completion of backup and recovery processes, Spanning Backup for Office 365 utilizes multiple layers of incremental retries and back-off code when we receive indications of throttling from Microsoft. Additionally, Spanning Backup for Office 365 performs high-load operations, like backups, during off-peak hours.
Both Spanning and Microsoft realize this is a critical issue to our shared customers. We have been and will continue working directly with Microsoft to ensure we are conforming to their coding best practices and to provide them with information and feedback concerning critical operations that encounter throttling.
It should be noted that Microsoft is impacting you, their customer for Office 365, by limiting your ability to utilize enterprise-class data protection products, such as Spanning Backup for Office 365. We are confident in our ability to completely and accurately back up your Office 365 data, using the Microsoft APIs, assuming Microsoft enables us to access their APIs in the way that Microsoft designed them. The Microsoft terms & conditions and SLAs do not restrict access to your data, and the throttling is preventing you (and Spanning) from accessing your data in accordance with your agreement with Microsoft.
What can you do?
As mentioned above, we will continue working directly with Microsoft regarding this throttling restriction. We also encourage you to reach out to Microsoft and let them know that highly available access to the data in your Office 365 environment is critical to your business, and any disruption to your ability to protect your data puts your business continuity and compliance requirements at risk.
If you have any additional questions or concerns, please contact us at firstname.lastname@example.org.