Fix 'The form required to view this message cannot be displayed' in Outlook

Forms are the user interface templates and codes which are basically used for displaying up the information existing in the Outlook PST items and for this Outlook application stores local copy of each and every customized form in cache. But when any kind of problem associated with Outlook forms or form cache occurs then you will not be allowed to have access to any of your data existing in PST items and errors like 'The form required to view this message cannot be displayed' error comes up on screen.

One such practical situation is when you are trying to open an important PST item but instead of displaying up the data, the application shows you the following error message on screen:

"The form you selected could not be displayed. Contact your administrator.“

Or

"The form required to view this message cannot be displayed. Contact your administrator."

If any Outlook item is using custom form to display its information, Message class field is responsible for the form name arrangement. After you click on the item, Message class field observes which form would be needed for the same and then Outlook searches for the specified form in the following locations: 

Memory: If more than one item is using the same form then Outlook uses the form which it has in memory rather than new one

Forms cache: to know if you have used a form before or not

Current folder: In case of form unavailability in cache, Outlook checks if form was published to current folder.

After the current folder, Outlook checks if form is available in Personal Forms Library and Organizational Forms library.

The Web Forms Library: Outlook also makes effort to search for the HTML version of form if HTML based forms have been created

By default, file size limitation of form cache is set as 2048 Kilobytes by Outlook and the unused form is removed by exceeding of the default file size. You may find entite information about the forms and its cache in Frmcache.dat file. But in case of form PST corruption Microsoft outlook, you can make use of Scanpst.exe Inbox repair tool to repair the form as well as PST corruption issues but in case of external corruption reasons like unexpected system shutdown or virus attack it does not prove to be useful one thus in this case PST Repair tool would be the best possible option