Outlook Internal Exchange Error 80000000? Try these fixes

Outlook and Exchange are the backbones of a corporate organization’s communication and things can get very ugly for the organization if these two applications stop communicating with each other. One such issue is the Outlook internal Exchange error 80000000, in which, an Outlook client cannot communicate with the Exchange server locally (although, the external connection is working fine) and throws the error 80000000. Usually, the following type of message is shown:

Outlook Internal Exchange Error 80000000

The following are found to mainly cause the Outlook internal Exchange error 80000000:

  • HTTP Protocol: Due to the complexity involved with HTTP protocol (certificates, etc.), it is recommended that an Exchange server may be accessed by using the TCP/IP protocol. If the Outlook client is configured to use the HTTP protocol, then the Outlook client may show the error 80000000.
  • Improper configuration of the Server’s Security Product: If the Server’s security product (like F5) is interfering with the Outlook/Exchange communication, then you may encounter the Outlook internal Exchange error 80000000.
  • TLS Update: TLS is an improved version of SSL and if its latest update is not applied to the client system, then the Outlook client may become incompatible with the Exchange Server, thus causing the Exchange error 80000000 when accessed internally.

Set the Outlook Client to Use TCP/IP Protocol

As the Outlook client is having issues internally when using the HTTP protocol, setting up the client to use the TCP/IP protocol (as recommended when using the client in the internal environment) may solve the problem.

  1. Launch the Outlook application and open its File menu.
  2. Now, in the right pane, expand the dropdown of Account Settings and select Account Settings.
    Open Account Settings of Outlook
  3. Then, in the Email tab of Account Settings, double-click on the account using the Exchange server, and in the resulting window, open More Settings.
    Open the Exchange Account Settings of Outlook
  4. Now, in the Connection tab, uncheck Connect to Microsoft Exchange using HTTP and apply your changes.
    Uncheck Connect to Microsoft Exchange using HTTP
  5. Then, relaunch the Outlook client and check if it is working fine.

Edit the System’s Registry to Delete the HTTP Value

Outlook may show the internal Exchange error 80000000 if the HTPP settings of the system are not properly configured in the system’s Registry and properly configuring the same may solve the problem.

Warning:  Proceed at your own risk as editing the system’s registry may harm your data/system, if not done properly.

  1. Firstly, to be on the safer side, create a backup of the system’s Registry.
  2. Now click on Windows and search for Registry Editor.
  3. Then, right-click on the result of Registry Editor and select Run as Administrator.
    Open Registry Editor as Administrator
  4. Now navigate to the following path:
    HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp
  5. Then, in the right pane, delete the DefaultSecureProtocols value and close the Editor.
    Delete the DefaultSecureProtocols Value in the WinHttp Registry Key
  6. Now, restart your system and upon restart, check if the Outlook Exchange error 80000000 is cleared.

If the issue is still there and you are having issues when the Exchange server is accessed from the local network, then make sure that the local DNS server properly points to the local address of the Exchange server.

Enable TLS 1.1 and TLS 1.2 Protocols on the Client Machine

TLS (Transport Layer Security) is a successor to the old SSL (Secure Sockets Layer) or in simple words, TLS is an improved version of SSL. If the client device does not have TLS 1.1 and 1.2 enabled, then it may not be compatible with the updated Exchange server and thus cause the issue. In this scenario, enabling TLS 1.1 and TLS 1.2 on the client system may solve the problem.

  1. Launch a web browser and download the following Easy Fix file from the official Microsoft website.
  2. Once downloaded, launch the Easy Fix as administrator.
  3. Then follow the prompts on your screen to apply the fix and afterward, restart your system.
  4. Upon restart, launch a web browser and download the following update from the official Microsoft Update Catalogue website.
    Download the TLS Update KB3140245 from the Update Catalog Website
  5. Now download the update as per your OS and once downloaded, launch the downloaded update as administrator.
  6. Then follow the prompts on your system to apply the update and afterward, restart your system.
  7. Upon restart, check if the Outlook internal Exchange error 80000000 is cleared.

If that did not work, then check the following Microsoft URL to set up TLS as per their recommendations. If that did not work as well and your organization is using F5 security, then check if changing the encryption method of the F5 in the SSL Profile from default to DEFAULT auf ALL:!DHE-RSA-DES-CBC3-SHA solves the problem. Also, if the problematic client is using Windows 7 and the F5 security is installed on the server, then the time may have arrived to update the machine to Windows 10 as F5 creates a lot of issues (including the one under discussion) for Windows 7 machines.


Kevin Arrows

Kevin Arrows is a highly experienced and knowledgeable technology specialist with over a decade of industry experience. He holds a Microsoft Certified Technology Specialist (MCTS) certification and has a deep passion for staying up-to-date on the latest tech developments. Kevin has written extensively on a wide range of tech-related topics, showcasing his expertise and knowledge in areas such as software development, cybersecurity, and cloud computing. His contributions to the tech field have been widely recognized and respected by his peers, and he is highly regarded for his ability to explain complex technical concepts in a clear and concise manner.