Graph calendar Delta query always lead to a 503 Service unavailable UnknownError

LSE Odoo 6 Reputation points


We do use graph REST API to synchronise calendar events.

However, for some users, it always result in the same 503 error response for no apparent reasons.
I didn't find any relevant information over this error online.
We were able to reproduce the exact same issue using the graph developer tool at:

Request details:


503 - Service unavailable

    "error": {  
        "code": "UnknownError",  
        "message": "",  
        "innerError": {  
             "date": "2022-03-26T09:33:15",  
             "request-id": "...",  
             "client-request-id": "..."  


Thank you in advance for your response,

Microsoft Graph
Microsoft Graph
A Microsoft programmability model that exposes REST APIs and client libraries to access data on Microsoft 365 services.
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  1. Shivam Dhiman 5,951 Reputation points

    Hi @LSE Odoo

    Error 503 error response generally occurs when the service is temporarily unavailable for maintenance or is overloaded. You may repeat the request after a delay, the length of which may be specified in a Retry-After header as you can see in this documentation

    • Sometimes it can happen with throttling. Backing off requests using the Retry-After delay is the fastest way to recover from throttling. For more information, see throttling.
    • Additionally, you should always make new retry requests over a new HTTP connection.
    • You can retry the requests or increasing the timeout(if you are using any custom application increase the timeout for at least 2 min)

    Hope this helps.
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