Hello everyone,
Subscription: Zoho One
Data Center / Server: EU
When trying to integrate Office 365 into Zoho CRM via the Graph API for the first time, the process immediately crashes with the following JSON error payload:
{"status_code":404,"err_msg":"Invalid URL","iam_err_msg":"URL_RULE_NOT_CONFIGURED"}
The full redirect URL of the error window displays the following Microsoft Azure/Entra ID error details:
Integration Halted: The integration is fully halted, and no further progress can be made.
App Registration: Interestingly, inside the Microsoft Entra Admin Center under Enterprise Applications, "ZOHO CRM" does appear as an authorized application with the following Application ID: 59299f9f-31f7-42ed-8d0f-5debb0fc104d.
Domain Discrepancy: However, analyzing its properties reveals a crucial discrepancy: The Homepage URL returned by Zoho during this failed handshake is configured as [https://crm.zoho.com](https://crm.zoho.com) (US Domain), instead of the actual EU server domain (.eu) from which the integration was initiated.
Sign-in Logs: Reviewing the Microsoft Sign-in Logs shows multiple entries fluctuating between "Success" and "Interrupted", alongside a specific sign-in log error code: 650051.
The entire error behavior strongly indicates a callback routing mismatch on Zoho's end. The integration workflow is triggered from the Zoho EU server, Microsoft handles the authentication successfully, the Administrator grants permission, but Zoho then attempts to redirect the authentication token back to the US server (.com). Since our organization is fully provisioned on the EU cluster, no data record exists on the US tenant, causing the integration to fail and break downstream components.
Retry via Office 365 Graph API: Following the initial failure, retrying the Graph API integration results in an authentication loop, throwing this error:
Unable to Get SMTP Email - Outgoing Authentication Failure for : [user]@[your-domain].de : 535 5.7.3 Authentication unsuccessful
Retry via Office 365 IMAP OAuth: Attempting to bypass the Graph API by utilizing the traditional IMAP OAuth option fails with the following stack trace:
com.adventnet.vo.mail.account.MailAccountException: Login failed.
To isolate this from the Microsoft infrastructure side, we have verified that the MS 365 tenant is perfectly configured:
SMTP AUTH is explicitly enabled tenant-wide under Exchange Admin -> Mail Flow.
App Access Protocols: Outlook on the web, Outlook desktop, Exchange Web Services, Mobile, IMAP, and Authenticated SMTP are fully enabled in the MS 365 Admin Center under User Settings (these have also been toggled off and back on for testing to force replica updates).
Entra Clean State: Prior to the initial integration, all legacy or historical Zoho enterprise application entries and service principals were completely deleted in Entra ID to ensure a perfectly clean starting point.
Privileges: The user account executing the integration holds Global Administrator rights within the MS 365 tenant and full Administrator rights within the Zoho One organization.
Since this issue is locked on the application/database mapping layer, please escalate this to your Tier 3/Backend Engineering team to fix the EU-to-US endpoint routing misconfiguration for our tenant.
Since the front-end UI suppresses the configuration due to this routing error, this cannot be resolved via standard admin panels.
Has anyone in the community encountered a similar routing mismatch between the EU and US servers, or found a viable workaround for this specific deadlock? If anyone has faced a similar issue or has any insights, I would highly appreciate your feedback and any advice you can share!
Additionally, could a Zoho Developer or Backend Engineer please look into this EU account alignment and manually fix the endpoint routing misconfiguration for our tenant?
Thank you all in advance for your support and feedback!