What Causes Outlook Error 0x80040900, and its Solutions

Have you ever faced an Outlook error message? Do you encounter such a message which completely makes you upset and frustrated? Outlook Error 0x80040900 is likely one of them.

Microsoft Outlook is an email client that offers various services to the users. Not only but also Outlook users can share all the mailbox items like emails, journals, calendars, contacts, tasks, etc. Most of the Outlook errors get solved by simply restarting the application. However, here we’ll carry forward our discussion regarding error code 0x80040900 which occurs during send/receive operations.

What Causes Outlook Error 0x80040900, and its Solutions?

Let’s look at the most common causes that may result in ‘0x80040900’, and it’s corresponding appearing solutions:

Network Connectivity

The poor network connection can make it difficult for you to access your Outlook data files. Essentially, the PST file is located on a network server, and bad network connection can result in hardware failure. As a result, PST files become inaccessible. To resolve this, make sure that your Internet connection is active and has a fast coverage. However, restarting your internet connection might also help in order to recover the problem.

Oversized or Corrupt PST

When the size of the PST file exceeds the limit (i.e. 50GB then the file may become corrupt or simply result in send-receive error ‘0x80040900’. You may resolve it using Microsoft built-in (Scanpst.exe) to fix PST file corruption. Moreover, the Microsoft repair utility cannot handle large-sized. And if the corruption is severe then, in that case, the software tool can help you overcome the Scanpst.exe limitations in the most efficient manner described below.

  • Fix severely corrupt PST files.
  • Prevent further corruption by splitting and compacting large-sized PST files.

Update Antivirus and Firewall Settings

Sometimes, an anti-virus software with email scanning features can cause issues that may result in Outlook ‘0x80040900’ error. This error occurs in case your server ports are getting blocked by Firewall. You can simply fix this error by temporarily disabling the anti-virus and Firewall settings and further check if it resolves the problem.

Note: Also, ensure you enable antivirus and firewall settings after you fixed the issue.

Incorrect Email Account Settings

Outlook error code 0x80040900 caused by an error in your email client setup. Essentially, error in the incoming/outgoing server’s name or server authentication indicates in error ‘0x80040900’. However, you can fix this by verifying that you have specified the correct settings for your Outlook email account. For this, you need to be admin and follow these steps:

  • Open your Outlook application.
  • Then click on File -> Account Settings -> Account Settings.
  • From their Account Settings, a dialog box will appear and then click on the Email tab.

A Professional Outlook Recovery Solution Can Fix It!

If the above solutions do not work out effectively then you may check out the PST Repair Tool. The advanced algorithm will help you out and check where the actual problem persists. It restores all the database stored in the Outlook PST which includes emails, calendars, contacts, mail items. The tool will surely help you out in recovering your data as it not only repairs the corrupted data but also recovers the deleted emails and other inbox items. I hope you found it helpful


Outlook keeps popping errors and makes its users panic. But in such a situation, the key to resolve the issues is patience you have to wear. To fix Outlook error 0x80040900, you can use these effective methods. I hope, you got the correct answer. Thanks for reading!

About The Author:

As a lead technical writer, I know the technical problems faced by office and professional users. So, I decided to share all my technical knowledge through this blog. I love helping you with tough challenges when dealing with technical issues.

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