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GroupDocs.Viewer for .NET v1.6 won't load a certain PDF doc


No problem loading in Acrobat, it’s ~37Mb, 84 pages (and has a lot of detailed 2D drawings). No problem loading other files with more pages or of larger size.

Not out of resources on the server, no explicit error message, first 2 thumbnails get created but noting happens after that.

Is there a log somewhere to figure out what’s going on or is this a bug ?



Hello James,

We are sorry to hear that you have this issue.

From your post we conclude that you are using GroupDocs.Viewer for .NET version 1.6, is that correct?

If yes, please try to update the GroupDocs.Viewer, because the version 1.6 is very old, the newest is the version 2.3.0. During this period a lot of fixes were added to the GroupDocs.Viewer, and maybe the problem with the specific document is already solved in the version 2.3.0.

However, if GroupDocs.Viewer will not display the document correctly even after the update, please send us that document and we will investigate it. If the document is confidential, you can upload it to the Dropbox or some other file sharing service and send a link to the

About logging. Yes, GroupDocs.Viewer has logging mechanism, but is also is present in the latest versions, not in the 1.6. For enabling it, you need to invoke the static method Groupdocs.Web.UI.Viewer.SetLogFilePath(path_to_the_file);

Please notify us if you will have any issues or questions, we will be glad to help you.


The issues you have found earlier (filed as WEB-1054) have been fixed in this update.

This message was posted using Notification2Forum from Downloads module by groupdocs.notifier.


Hi Denis,

Thanks for that reply, here’s some clarifications and an update:
1) yes, was using GroupDocs.Viewer for .NET version 1.6
2) updated to 2.3.0 and:
- good news: the document does now display
- bad news: it’s very slow

#Pages: 84
File size (.PDF): 36Mb
Time to display first image/thumbnail: 1:46 mins
Time to display all pages: 9 mins

Of course our users judge us (and Groupdocs ;-)) against Acrobat on the desktop (< 2 secs for all pages) so we need to do much better.

It’s a customer file with identification (includes 2D CAD info) so can only share it privately/confidentially and will send in an email as you suggested.

Did enable the log which I’ll attach here and send email next.



Hello James,

We have obtained your document and log file, thanks. We reproduced the issue that you’ve described - yes, there is abnormally long rendering time, it usually should be much faster. Our developers are already working with this PDF. We will notify you when this bug will be fixed.

Sorry for the inconvenience.


Hello James,

We are sorry for such long delay, unfortunately this issue is not trivial. There is an intermediate solution which can deliver a significant result. The document processing is done in 2-3 times faster on the server if the “.UseHtmlBasedEngine(true, true)” method is used. In this method the first parameter enables a usage of the HTML-based rendering mode, and second - using a PNG images instead of SVG. This combination gives the described performance improvement. Of course, all this is valid only for your specific document “2014_08-01 Pyara Construction Set.pdf”.

Once more, sorry for the inconvenience. When there will be the final solution of the problem, we will immediately notify you in this forum thread.