TechTip: Receiving a "file type is not supported" error message when trying to share a PDF in Cisco WebEx

Cisco WebEx is one of the most feature-packed web conferencing platforms on the market today. Among its many features, it lets the presenters directly "share" (display on the screen) the contents of various file formats, by uploading them into the WebEx session instead of simply streaming the live view of their screen for that application. This offers multiple benefits, such as giving participants the ability to switch between multiple shared documents on their side, annotate the documents in WebEx, and save those annotations. Multiple file formats are supported for direct sharing, such as Microsoft Word documents, Excel spreadsheets or (Adobe) PDF files.

The Problem

However, you may at some point (typically after a system refresh or reinstallation/upgrade of your PDF viewer program) come across the following error message when attempting to share PDFs through your WebEx client: "We could not share this file because this file type is not supported for file sharing. Either convert the file to a supported format or use application or screen sharing to share this file."


The error message is rather obscure and doesn't point at all at what the root cause could be. If trying the feature for the first time - one might even assume that PDFs are just not supported by WebEx, period, and give up. I was able to share them before, so I went looking for a fix.

The Solution

Turns out that WebEx Document Viewer relies on the native local file format viewer to render and share the file contents. What this means for this particular problem is that, for some reason, your system does not have the default viewer configured for PDF files.

Note: When this was happening on my system, Adobe Reader was set to be the default viewer for PDF files, however, it was done through "Default Programs" setting in the Windows Control Panel, and evidently that was not enough.

The easiest way to fix this is to go into your preferred PDF viewer application, go through it's properties, find and set the native setting selecting it as the default viewer. Do this even if it already has this option selected - it was already on mine, but until I re-selected and applied that option in Acrobat, WebEx was refusing to recognize it as the default application, despite Windows using it to open PDF files.

Adobe Acrobat

In Adobe Acrobat this setting can be accessed using the following steps:

  1. Open the Adobe Acrobat application
  2. Navigate to the Edit --> Preferences menu (or press Ctrl+K)
  3. In the menu on the left, select the "General" category
  4. On the very bottom of the right section of the screen, click "Select Default PDF Handler"
  5. Pick the desired Adobe product and click OK


If you are using non-Adobe products as your default PDF viewers, search the internet for steps on how to set them as default, but try to find the native setting and not rely on the Windows "Default Programs" or "Open with... --> Always use..." setting. Evidently, it doesn't always work.

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