Outlook Contacts API via Celigo returning intermittent 500 errors (works in mock/test step)

Integrator.io
1

Hi all,

I'm trying to import contact data into Outlook using the Microsoft Graph API through Celigo.
The connection is an Outlook integration using OAuth 2.0, with delegated permissions granted via the standard Microsoft login popup during authorization.
The initial test (with <10 contacts) worked fine, the contacts were created successfully.

However, now I’m consistently getting intermittent 500 Internal Server Errors when sending the actual contact data during a flow run.

Strangely, when I send mock/test data from within the same flow step, the request succeeds and returns 200 OK.

Has anyone experienced this behavior before?
Could this be related to Entra ID app permissions?

App is registered in Entra with Contacts.ReadWrite and User.Read scopes, and uses OAuth 2.0 via iClient:

The image shows a table of Microsoft Graph API permissions with their claims, types, and how they were granted. (Captioned by AI)
The image shows a table of Microsoft Graph API permissions with their claims, types, and how they were granted. (Captioned by AI)2228×514 64.4 KB

Error:

The image shows an error message indicating a "500 Internal Server Error" from Microsoft Outlook Contacts, classified as "Intermittent," with HTTP response details displayed on the right. (Captioned by AI)
The image shows an error message indicating a "500 Internal Server Error" from Microsoft Outlook Contacts, classified as "Intermittent," with HTTP response details displayed on the right. (Captioned by AI)2215×322 26.3 KB

Mockup Send:

image
image347×155 2.44 KB

Any ideas would be appreciated!

Thanks.