SOLVED! AADSTS900561: The Endpoint Only Accepts POST Requests

Nowadays, for office work, Windows users rely on Microsoft 365 which is why most have Microsoft 365 accounts. In most of the cases, people could sign into their Microsoft 365 accounts and make use of Microsoft 365 services at will. However, the sign-in process of Microsoft 365 accounts still leaves something to be desired and “AADSTS900561: The endpoint only accepts POST requests” is a prime example. Read to the end if the same issue is preventing you from signing into your Microsoft 365 account. 

A List Of Solutions

 “AADSTS900561: The Endpoint Only Accepts POST Requests”

Clear Cookies

Clearing cookies in your web browser may help you get rid of a lot of issues including AADSTS900561. For the sake of convenience, let’s say Google Chrome as your web browser. Go through the steps down below to clear the cookies:

  • Step 1: Open Google Chrome and hit More (⁝) option in the top right corner.
  • Step 2: Select More tools and choose Clear browsing data.
  • Step 3: Set the Time range to All time, check the Cookies and other site data checkbox and hit Clear data.

After you finish, all the cookies should now be cleared from your browser. Now you may log in to your Microsoft 365 account and see how things turn out.

Allow Third-Party Cookies

Another solution for “AADSTS900561: The endpoint only accepts POST requests” is to allow third-party cookies in your web browser. Again, let’s assume that you use Google Chrome to access the Internet.

  • Step 1: Open Google Chrome and hit More (⁝) option in the top right corner.
  • Step 2: Select Settings then choose Privacy and security in the left pane.
  • Step 3: Hit Cookies and other site data and tap Allow all cookies.

Lastly, close everything, launch a new browser session and sign into your Microsoft 365 account.

Apply Changes To Internet Properties

  • Step 1: Press Windows + R key to open Run.
  • Step 2: Type inetcpl.cpl in Run and press Enter.
  • Step 3: Choose the Privacy tab and tap Sites.
  • Step 4: Enter the URL you are using to log in to your account and click Allow. Press Ok to close the window and determine whether the issue persists.

Uninstall And Reinstall

In the beginning, uninstall Microsoft 365 from your device via Uninstall a program in Control Panel. Next, restart your computer and the moment the screen comes back on, reinstall Microsoft 365 using the administrator account.

Get In Touch With Customer Support

If none of the above works, it’s time to contact customer support of Microsoft. By following the instructions of support employees, you should be able to fix “AADSTS900561: The endpoint only accepts POST requests” before long.

Causes Of The Error

 “AADSTS900561: The Endpoint Only Accepts POST Requests”

All in all, quite a few factors could affect the sign-in process of Microsoft 365 accounts. For instance, the way our browser manages third-party cookies could result in errors such as AADSTS900561. Aside from that, the inverter properties of your PC may complete things during the sign-in process as well.

How Do I Repair Office 365 On Windows?

How Do I Repair Office 365 On Windows?

  • Step 1: Press Windows + S key and type Control Panel in the search bar.
  • Step 2: Select Program then Program and Features option. 
  • Step 3: Navigate and Right-click on Office 365 and click Repair.

Here you will be provided with two options i.e. Quick repair and Online repair option. You can choose either of them depending upon the urgency and severity of the problem. Overall, Online Repair is capable of performing more extensive checks and is equipped with more capabilities than Quick repair.

What Must Be Done If I Cannot Recall The Password Of My Account?

For resetting the password for your account, go to and follow the onscreen instructions. For recovering Microsoft accounts, go to and follow the onscreen instructions.

What Is the Difference Between Microsoft 365 and Office 365?

In a nutshell, Office 365 is a cloud-based suite of productivity software that includes Outlook, Word, PowerPoint and others. On the other hand, Microsoft 365 is more of a service package that includes Office 365 as well as various other services such as Windows 10 Enterprise. There is also the fact that the Office 365 subscriptions do not include any of the additional Enterprise Mobility + Security solutions provided in Microsoft 365. Nonetheless, Office 365 Business Premium does have extraordinary capabilities that can support bills, client management, appointment scheduling, and other tasks. 

Lastly, Office 365 plans are less expensive than Microsoft 365 plans in terms of cost. Plans start from $5/month for Office 365 and go up to $12.50/month per user.

Is There A Limit To The Number Of Devices That I Can Install Microsoft 365?

Microsoft 365 can be installed on all of your devices but you can only log in to a maximum of 5 devices at a time. Various devices like PCs, Macs, iPads, and smartphones are eligible. To keep your account sign-in limit under control, the Office automatically signs you out from other devices if the number goes beyond 5. To use Office on a device where you’ve already logged out, simply sign back in. 

The Office stays operational as long as you are logged in. The moment you sign out, your account license is erased and the app disabled. You can only browse and print files but you cannot create or change them.

A Beginner’s Guide

  • Using the “TELL ME” option in your Office 365, you may enter words or phrases to quickly get to features you want to use next. That comes in handy in many situations, especially during draw-out works.
  • OneNote’s notebooks allow you to store links, save images, and so on which allows you to keep research notes in one place.
  • Smart Lookups could help you retrieve data in mere seconds and save you a lot of time. To make use of the Smart Lookup feature, select Tell me from the top and type in Smart Lookup. Next, pick a word or phrase, hit right-click, and select Smart Lookup. 
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