When someone tries to open an Office file in their local client instead of using Office Web Apps or directly tries to edit a document in Office, the above error might show up or this one;
The document could not be opened for editing. A Microsoft SharePoint Foundation compatible application could not be found to edit the document.
- Check whether the IEx64-bit client is used and if so, change to the x32-bit version
- Check the IE Add-Ons via;