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JavaScript error when following demo


I tried to set up an empty ASP.NET webforms project and more or less follow your How to sample.

Then VS2012 would notify me of a Javascript error and the PDF would not load. The loading icon turns endlessly next to the message: "Loading your content". The message in VS2012 is:

Unhandled exception at line 6, column 96401 in http://localhost:58785/document-viewer/GetScriptHandler?name=GroupdocsViewer.all.min.js

0x800a1391 - JavaScript runtime error: 'JSON' is undefined

Then I tried to follow the sample exactly but still get this error. Can you explain why I get this error and point me in the right direction?

Thanks in advance.

Hello Robert,

We are sorry to hear that you have such issue and would like to help you to resolve it. We investigated and reproduced the issue. We assume that you use IE browser. To resolve the issue please turn off “Compatibility View” mode in your IE browser as shown on screen shot.

Other way to solve this issue is to enable last IE engine with this code:

Please note that minimum supported IE version for GroupDocs Viewer for .NET library is IE8. If you use IE lower than 8 version please update your IE browser.

If you will have more questions please feel free to contact us.

You are right. I noticed that localhost had been added to compatibility view. Somehow I missed that point.

Thank you so much for your help.


Hello, I was wondering if groupdoc viewer can run in compatibility mode now, or if it still needs to be turned off?

Thank you,



Hi Karen,

Thank you for coming back. In case using the latest Viewer and IE 11 you can run it in the compatibility mode.

Best regards.