Cause and Solution of Yahoo! Messenger Error 400

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I was using my Yahoo messenger account for a long while; I haven’t found any issue, but last ever, when I was trying to open it the error 400 welcomed me.

How to fix this issue now?

When Yahoo Messenger users experienced the Yahoo messenger error 400 while trying to access the account or IM; it will be difficult to use. Well, no worries; we have this blog for you to fix the Yahoo mail error code 400.

Yahoo messenger error 400 displays in various forms

  • Error 400 Bad Request
  • Bad Request – Your browser sent a request that this server could not understand
  • HTTP Error 400 – Bad Request
  • HTTP Error 400 – The request hostname is invalid
  • Bad Request Error 400
  • Error 400 – Bad request. The request could not be understood by the server due to malformed syntax. The client should not repeat the request without modifications
  • Bad Request – Invalid URL

Causes for Yahoo messenger error 400 while using it

  • If you have a corrupt download or incomplete installation of Yahoo! Messenger Application software
  • When the Windows registry is corrupted which comes from a recent Yahoo Messenger-related software change
  • Some cases occur when a virus or malware infected the Windows system files or Yahoo! Messenger-related program files
  • Another program mistakenly deleted Yahoo! Messenger-related files or software

The solution of Yahoo! Messenger Error 400

In order to fix this error; you have to go for a fresh installation of Yahoo Messenger application on your computer or device. We have this solution for you in two steps; first is to go with uninstalling and then the fresh installation.

Step 1 – Uninstall Yahoo Messenger

  • First, go to the Start button and click on Control Panel
  • Here, you need to click on Start at the bottom left of the screen and then right-click to open the Start Context Menu
  • After that, click on Programs and choose Programs and features
  • Now, click on Programs and Features
  • Here, you need to search for the program Yahoo! Messenger
  • Then click on Add or Remove Programs and look for Yahoo! Messenger under currently installed programs section
  • And, click on the Uninstall option from your Yahoo! Messenger
  • Finally, click on the Remove button from it
  • Now follow the on-screen instructions to complete the uninstall process
  • Your Yahoo messenger will be uninstalled immediately

Step 2 – Fresh installation Yahoo Messenger once again

  • Your first step is to go to and download Yahoo Messenger installer file here
  • As the installer or .exe file is downloaded, you just need to run it following the on-screen instructions for installing it once again
  • You can sign in once again with your Yahoo account credits

Furthermore technical issues in your Yahoo email account and face any problem, so relax and freely contact our Yahoo customer service support number via phone.


  1. Why is it that I am unable to open my yahoo email address. Please tell me why and sort out this problem for me as soon as possible, as I just can’t open my yahoo email address.

    M. R. Ferdinands

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