When Outlook is connected to Exchange Server, then it will show its status as ‘Connected to: Microsoft Exchange’ and the email communication will be smooth but in some circumstances the Exchange Server unavailable and gives the message that

‘The connection to Exchange Server is unavailable.’

The bad thing about this error is that you cannot open the mailbox and send/receive emails. Sometimes, the error occurs due to bad Internet connection and resolves after establishing a proper connection. But if the error remains to bother you, then you should look for various troubleshooting methods based on the cause of the error.

What causes error “Exchange Server is Unavailable”?

The Exchange Server is down

Getting the error in Outlook does not necessarily mean that fault is on your side, but the Exchange Server may be down at the time, and you can wait for it to start working again.

Third-party applications are stopping Outlook

There are several third-party applications like anti-malware, monitoring applications, etc. that can check other applications and stop them from working. Sometimes, the anti-malware software of your system may stop the working of Outlook.

Faulty add-ons in Outlook

Outlook uses several add-ons to serve different purposes, like checking grammar, conversion to PDF, etc. Because these add-ons are from the external sources, they can affect the performance of Outlook and disrupt its connection with the Exchange Server.

Fix the error “Exchange Server is Unavailable”

There are a few manual solutions to resolve this error. Let us see some of them:

By Restarting the Exchange Server services.

If the connection between Exchange Server and Outlook is broken due to the inactivity of the service, then you can restart it again and maintain the connection.

Go to the Windows Server menu, click Run, and input services.msc command. Then click Enter. After opening the list of all the services, locate the Exchange services and restart them.

By changing the permission level of data files

Because the data files are on the system like any other file, they have permission levels like Write, Read-only, etc. If the permission levels of the data files have been changed to Read-only, then you can change it back to Write.

Locate the data files from their respective locations. Generally, the data files are present in the Microsoft Outlook folder in the App data folder in C drive. Choose the data file of the Outlook account that you are currently using. Right-click and check its Properties. If it shows Read-only, then uncheck it and check the other option to Write. Now Restart Outlook.

Editing Registry Values

Incorrect registry settings can be a reason for the error “Exchange Server is Unavailable.” To fix this issue, you need to modify it. Follow the steps to edit the registry values:

Press Windows+R, type Regedit and click OK. Click Yes button on permission box. Then a Registry Editor window will get opened. In it, find HKEY_CURRENT_USER and then select Software in it. Now, navigate to Microsoft>Office>Outlook>RPC. On File, go to Edit, click New > DWORD. Type DefConnectOpts and press Enter. Right-click DefConnectOpts and click Modify. Give it value 0 and click OK.

Thus, the registry value has been modified.

Through Cache Resetting

Outdated storage data in the cache might be the cause for Exchange unavailable error. Using flushdns command, you can overcome this issue. This command execution will automatically delete the outdated information by resetting DNS cache server.

In Command Prompt (as administrator), run: ipconfig/flushdns

After the execution, close the Command Prompt. Then, try to connect Exchange Server once again.

With Third-Party Professional Software

When “Exchange Server is Unavailable,” you may not be able to perform emailing activities. But you can convert the OST files to PST and use in Outlook to establish email commutation. This conversion can be done using Kernel for OST to PST tool.

When you want to move OST data to some other platforms, then also this OST to PST tool can be used. The software saves Outlook OST emails to PST, Office 365, and Exchange. It converts orphaned or corrupted OST files also. The conversion is fully secured without any glitches or data loss. Intelligent filters, destination options, and interactive user-interface are prominent characteristics of the software.