Attachment file preview stopped working in Outlook. When you select an attachment (PDF, XLSX or DOCX file), an error appears in the Outlook preview window:
The file cannot be previewed because no previewer is installed for it.
This file cannot be previewed because there is no previewer installed for it.
Or
This file cannot be previewed because the following previewer has been disabled.
Let's see how to fix a viewer issue in Outlook.
First of all, of course, make sure that the appropriate program for viewing this type of file is installed on your computer. For example, Adobe Reader for PDF or Microsoft Excel for XLSX. Also note that the bitness of Outlook and the viewer must match. For example, if you have 32 bit Outlook and x64 Adobe Reader installed on your computer, viewing pdf files in Outlook will not work. Install the correct version of the viewer.
Then check the preview settings in Outlook.
- Go to File -> Options -> Trust Center -> Trust Center Settings -> Attachment Handling ( File -> Options -> Trust Center -> Trust Center Settings -> Attachment Handling ");
- Make sure that the option “ Turn off Attachment Preview ” is not enabled ;
- Click on the “ Attachment and Document Previewers” button;
- Check that the viewer application for the desired file types is enabled in the application list.
- Then go to the General section of Outlook settings and in the User Interface options section select the Optimize for compatibility mode.
Then check the association settings for previewers in the registry. Run regedeit.exe and go to the registry branch depending on the version of Outlook:
- Outlook from Office 365 (Microsoft 365 Apps for enterprise) - HKLM\SOFTWARE\Microsoft\Office\ClickToRun\REGISTRY\MACHINE\Software\Microsoft\Windows\CurrentVersion\PreviewHandlers
- x86 version of Outlook from Office 2021/2019/2016 - HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers
- x64 outlook- HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\PreviewHandlers
Check that the specified branch has the following registry settings (each setting for a specific file type and application):
| Parameter name | Meaning |
| {00020827-0000-0000-C000-000000000046} | Microsoft Excel previewer |
| {21E17C2F-AD3A-4b89-841F-09CFE02D16B7} | Microsoft Visio previewer |
| {65235197-874B-4A07-BDC5-E65EA825B718} | Microsoft PowerPoint previewer |
| {84F66100-FF7C-4fb4-B0C0-02CD7FB668FE} | Microsoft Word Previewer |
| {DC6EFB56-9CFA-464D-8880-44885D7DC193} | Adobe PDF Preview Handler for Vista |
If one of these parameters is missing in the registry branch, create it manually (type REG_SZ ).
If the registry already has a value of type REG_EXPAND_SZ with the specified ID and value @%CommonProgramFiles%\Microsoft Shared\Office16\oregres.dll,-403, it must be removed.
In my case, I had the parameter:
{00020827-0000-0000-C000-000000000046} = @%CommonProgramFiles%\Microsoft Shared\Office16\oregres.dll,-403
I removed it and created a new REG_SZ parameter:
{21E17C2F-AD3A-4b89-841F-09CFE02D16B7} = Microsoft Visio previewer
After that, the preview of Excel files in Outlook began to work normally.
If Outlook does not preview PDF files using Adobe Acrobat Reader (it is in this program, this is important!), Check for the following registry value AppID = {534A1E02-D58F-44f0-B58B-36CBED287C7C} in the registry branch HKLM\SOFTWARE\WOW6432Node\Classes\CLSID\{DC6EFB56-9CFA-464D-8880-44885D7DC193}
If on a PowerToys computer, make sure that the Enable PDF Preview option is disabled in its settings (in the File Explorer add-ons section)
If all else fails, try reinstalling both programs (both Outlook and Viewer).