# Error: AADSTS50194: single-tenant application (Microsoft 365)

Source: https://catalystgroup.gg/docs/email-delivery/error-aadsts50194-single-tenant/
Updated: 2026-10-19 · By Duane Garner

The Tenant ID field holds a shared value such as "common" instead of your own tenant. Enter your Directory (tenant) ID.

This article is for sites using the **365 / Outlook** mailer where the token request to Microsoft fails with code `AADSTS50194`.

 

> **The error as you see it:** `Microsoft 365 token request failed: AADSTS50194: Application '…' is not configured as a multi-tenant application. Usage of the /common endpoint is not supported for such applications…`
>  
> Shown by the **365 / Outlook** mailer, in the failed-send banner, in **Tools → Debug Events** and in the **Email Log**.

 

## What this error means

 

Before each batch of sending, the plugin asks Microsoft Entra ID for an access token at an address that includes the **Tenant ID** you saved. Microsoft also accepts a few shared values there, such as `common` and `organizations`, which mean "work out the tenant for me". That shortcut is only allowed for apps registered as multi-tenant. Your app registration is single-tenant (the normal and safer choice), so Microsoft wants your own tenant named explicitly.

 

## Common causes

 
- **The Tenant ID field contains `common`, `organizations` or `consumers`**, often copied from a generic example.
- **Settings imported from another plugin** stored one of those shared values.
- **The field holds something other than the tenant**, such as the Object ID of the app, and an older setting fell back to a shared value.

 

## How to fix

 
1. Open your app registration
  Go to `https://entra.microsoft.com/`, then **Identity → Applications → App registrations**, and open the app you created for this site.
2. Copy the tenant ID
  On the app's **Overview** page, copy **Directory (tenant) ID**. It is a long ID in the form `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`. While you are there, also note **Application (client) ID**.
3. Leave the app single-tenant
  There is no need to change **Supported account types**. Making the app multi-tenant would also remove the error, but it opens the app to sign-ins from other organisations for no benefit.
4. Update CRM-NG SMTP
  In **CRM-NG SMTP → Settings → General**, with **365 / Outlook** selected, paste the value into **Tenant ID**. Your tenant's domain, such as `yourcompany.onmicrosoft.com`, also works. Check that **Application (Client) ID** matches the app. Press **Save Settings**.
5. Send a test
  Go to **CRM-NG SMTP → Tools → Email Test**, fill in **Send To** and press **Send Email**.

 

## Verify it worked

 

The test page shows "Test email sent successfully! Check your inbox to confirm delivery." The error no longer appears in **Tools → Debug Events**.

 

## Notes

 
- If you have constants in `wp-config.php` for this mailer (`CRMNG_SMTP_*`), the settings page cannot change them. Edit the constant for the tenant ID there instead.
- A different code, AADSTS90002 or AADSTS900023, means the tenant ID was not found or is not well formed. See [400 invalid_request](https://catalystgroup.gg/docs/email-delivery/error-400-invalid-request/).

 

## Related

 
- [Microsoft 365 / Outlook](https://catalystgroup.gg/docs/email-delivery/mailer-microsoft-365/)
- [Error: 400 invalid_request (Microsoft 365)](https://catalystgroup.gg/docs/email-delivery/error-400-invalid-request/)
- [Error: InvalidAuthenticationToken: token expired (Microsoft 365)](https://catalystgroup.gg/docs/email-delivery/error-invalid-authentication-token/)
- [Troubleshooting email delivery](https://catalystgroup.gg/docs/email-delivery/troubleshooting/)