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Outlook on the web (earlier known as Outlook Web App) is the online version of a desktop Outlook application. If you are working remotely, it will be beneficial to log in to your Exchange account using Outlook on the web. It will retrieve your mailbox with all its folders. But, if it does not find your web address after connecting with the server, it gives a bad request error with the number 400.
"This error (HTTP 400 Bad Request) means that Internet Explorer was able to connect to the web server, but the webpage could not be found because of a problem with the address."
When the user proxies an HTTP request from an Exchange Server 2013 Client Access Server) or Microsoft Exchange Server 2016 (running client access service) to an older version of Exchange server, then you may get a bad request error like the above.
Mostly this issue is found in Exchange Server 2016 (Enterprise & Standard Edition), Exchange Server 2013 (Enterprise & Standard Edition), and Exchange Server 2010 (Standard & Enterprise) environments.
Also, Exchange Server 2013 Client Access server show the following in the Exchange logs ( <Exchange Server Install Path>\Logging\HttpProxy\<Http resource>):
Moreover, the Exchange Server 2010 and Exchange Server 2007’s Client Access Server may have the following error message in their HTTPERR logs:
The cause of the error is the presence of your account in the multiple Active Directory Groups. The error may occur in the proxy request form the Client Access Server of Exchange Server 2016 or 2013 to that of Exchange Server 2010.
To resolve the issue, you need to remove the user account from multiple Active Directory Groups. Also, increase the MaxFieldLength and MaxRequestBytes subkeys for all Exchange Server 2010 CAS.
First, we will learn to change the subkey parameter in the Exchange Server 2010.
|Value Name||Value Type||Value Data||Value Base|
The second method is removing the user account from the different role groups of the Active Directory. A user account can be a member of multiple groups. The Bad Request error occurs when a user account that is running the proxy service is a member of multiple groups.
You can remove the user account from the group using the Exchange Shell cmdlets. Here is the example –
The command will remove the account name Jonathan from the Networking Role Group.
The above-mentioned methods remove the causes affecting the proxy requests and giving the bad request error 400. But such error may occur due to the corruption in Exchange mailbox too. The manual methods will not remove the corruption and the issue will keep affecting in Outlook Web Apps. So, you should also scan the EDB file for corruption issues. Kernel for Exchange Server can fix database from any kind of corruption and align the recovered data. Later, you can export data to another Live Exchange that is accessible and not showing any errors.
It is a top-rated Exchange Recovery software for the Exchange Server corruption issues. It can access the offline Exchange database files and scan them for any possible corruption. It will recover deleted mailbox in Exchange server back. It will show you a clean preview of the recovered data and allow you to save the recovered items in the multiple output formats suitable to you.
HTTP 400 Bad Request error can occur when Exchange 2013/2016 Client Access Server proxies an HTTP request to an older version of Exchange Server. To fix this error, you need to remove the user account from some AD groups or change MaxFieldLength and MaxRequestBytes subkey values for Exchange 2010.