The code (429) in Veeam Backup for Microsoft 365 indicates that you have exceeded the rate limit imposed by Microsoft. It occurs when too many requests are made to Microsoft within a specific time frame. Here are some recommendations in handling the (429) throttling issue:
• Upgrade Veeam. Veeam has released Veeam Backup for Microsoft 365 22.214.171.12407 which addresses the (429) warning.
• Allow retries. (429) warnings normally clear up on a retry. Retries should be enabled by default. If retries are not enabled, you may turn these on in the last tab of the job settings.
• Temporarily disable EWS Throttling Policy.
- In your admin, open the Support drop down and select Help & support to open the search window.
- Search for EWS Throttling Policy Increase and Run Test. Once the test is complete you will have the option to temporarily increase the throttle.
- After selecting Update, you will receive a Success! message that the throttle has been increased.
Additional information can be found here at Veeam and Microsoft.
If the (429) error persist, please reach out to Managecast. We’re happy to assist in troubleshooting and resolving your issue.