# Issues with Microsoft SSO (404 Error) – Solution

**Category:** FAQ

**Version:** 1.0

**Last updated:** Januari 22, 2026

**Author:** Any2Info

### Summary

Over the past few days, some customers have experienced issues with Single Sign-On (SSO) via Microsoft. In specific situations, this can result in a **404 error** during the login process. This issue is caused by a limitation on the maximum allowed URL or query string length within IIS.

By making a small configuration change in the `web.config` of the affected services, this problem can be resolved.

***

### Symptoms

* Logging in via Microsoft SSO occasionally fails
* The user encounters a **404 error** during or immediately after the Microsoft login
* The issue does not occur consistently, but only for specific accounts or scenarios

***

### Cause

Microsoft SSO relies on redirects that include relatively long URLs and query strings.\
By default, IIS enforces a limited maximum length for these values. When this limit is exceeded, IIS returns a 404 error.

***

### Solution

By increasing the maximum allowed length for the URL and query string in IIS, Microsoft SSO can function correctly again.

Add the following configuration to the `web.config` of the relevant service(s):

The relevant services are:

* AppsService
* Platform
* Apps

```xml
<system.webServer>
  <security>
    <requestFiltering>
      <requestLimits maxUrl="16384" maxQueryString="8192" />
    </requestFiltering>
  </security>
</system.webServer>
```

### Impact

* No functional impact on other parts of the application
* The change is safe and limited to request validation
* Recommended for all environments that use Microsoft SSO

***

### Need help?

If you need assistance applying this change, please contact our support department.

* <Support@any2info.com>

### Changelog

| Version | Date              | Change                               |
| ------- | ----------------- | ------------------------------------ |
| **1.0** | Januari  22, 2026 | Initial documentation version added. |