Before moving on with the solutions to fix the no default mail client issue, make sure you have a mail client installed (Outlook or Thunderbird just not the Mail app). Moreover, you can try an SFC scan. Also, check if clean booting your system resolves the issue. You can also create a different Outlook profile to check if the corrupt profile was causing the issue.

Solution 1: Set the Default Mail Application

You may encounter the mail client issue if the default mail application is not set or recognized by your system. In this scenario, setting the default mail application may resolve the problem. If the issue is initiated due to another application e.g., Adobe Acrobat, then changing that application preferences may solve the problem (we will discuss the process for Adobe Acrobat, you may have to make it work for the problematic application).

Solution 2: Perform a Repair of Office Installation

You may encounter the mail client issue if the installation of Microsoft Office is corrupt. In this context, performing a repair of the office installation may solve the problem. If the issue is still there, then copy the VCRuntime140_1.dll (C:\Windows\System32\vcruntime140_1.dll) from a working computer and see if this resolves the issue. If that did not resolve the problem, then you may have to reinstall the office/problematic application (but do not forget to reboot the system before reinstallation). If you are using more than one version of Office, then remove all versions & install only one (if the problematic application is the 32-bit, then check if installing the 32-bit version of Office resolves the issue). You may try the Microsoft Office Uninstall Support tool to remove Office. If you do not want to use a 32-bit Office, then check if disabling the Preview Pane.

Solution 3: Manage the Conflicting Applications

The mail client issue can be triggered by any of the applications on your system. In this context, managing the conflicting applications (changing the application’s settings, disabling it, or removing it) may solve the problem. The first step should be to identify the application causing the error. To do so, when the mail client message is shown, right-click on its icon on the Taskbar of your system & it will show you which application is causing the error message. You can also check the Task Manager of your system for the application causing the issue. Following solutions for the relevant applications are reported by the users to solve the problem.

Check Your Antivirus

Some users reported that interference from their antivirus was causing the issue. For example, Avast Cleanup is reported to cause the issue if your Office application is added to the sleep settings of the Avast. Also, you may have to remove McAfee (if being used) as it is reported to cause the issue. You can confirm by temporarily disabling your antivirus (but be careful & at your own risk as disabling antivirus may expose your system to threats)

Remove Outlook Add-in

If the issue is still there & to confirm if any of Outlook’s add-ins is causing the issue, right-click on the Windows button & choose Run. Then execute the Outlook.exe /safe & check if the system is clear of the mail client issue. If so, then enable add-ins one by one till you find the problematic add-in.

Disable Cortana

Delete the Dynamics CRM Leftovers

Many users reported that they encountered the issue due to leftovers of the previous installation of Dynamics CRM. If the issue is still there, then you can use any of the process explorer applications to find out the problematic application.

Solution 4: Use the Registry Editor

If the issue is still there, then some registry edits may let a user get rid of the problem. But before moving on, make sure to create a backup of your system’s registry. Warning: Proceed with extreme caution & at your own risk as editing the registry of your system requires a certain level of proficiency & if not done properly, you may cause everlasting damage to your PC/data. Launch the Registry Editor as Administrator & use the following registry edits one by one to check if that resolves the mail client issue.

Set the Default Key to Microsoft Outlook

Rename the PreFirstrun Key

Add the Bitness String Value

Rename the Sub-Key of Components

Add the DLLPath & DLLPathEx keys

Delete the Mail Key

If the issue is still there, then try a 3rd party application (like Thunderbird) or a cleaning application like PatchCleaner to solve the problem. If the issue started after a Windows update, then check if removing that update solves the problem. If the issue persists & you are desperate enough, then either try to perform a system restore or clean installation of Windows may resolve the issue.

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