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Viewer and Compare problems


My superiors have asked certainty in the resolution and a short time for the troubleshooting. Otherwise they will have to act accordingly.

Viewer version 2.10

With UseHtmlBasedEngine(true, true) there are no refresh problems in
changing the contents to view, but we have a wrong visualization of the
characters with certain words in PDF documents. (pdfProblems.png)

Using this configuration with IE8, besides the
already mentioned problem, with word files we have this situation (with, for
instance, IE11 the problem doesn’t occur). (wordProblems.png)

UseHtmlBasedEngine(false) we have no visualization problems, but the refresh of
the document doesn’t work (if the document, for instance, is a doc and we
change its contents, at the refresh the old version is uploaded – demo project and video sent to the forum on 30/04).<o:p></o:p>

With pdf files, then, clicking
inside the document an error is displayed – this error is not displayed with UseHtmlBasedEngine(true,
true) (fixed in version 2.11). (webpageError.png)

version 2.11

Besides the problems of version 2.10, with IE8, even using
UseVirtualScrolling(true) we have the problem fixed with the virtual scrolling,
that is the occurring of Javascript errors in loading documents with a high
number of pages, therefore there has been a regression. (javascriptError.png)

version 2.7 (version currently released with our product)

In this
version too the document refresh problem is present if we use UseHtmlBasedEngine(false),
besides the javascript pop-up with IE8 in the case of documents with many pages.<o:p></o:p>

If, on the contrary, we use UseHtmlBasedEngine(true, true), documents
are displayed in a wrong way (if, as in our case, the viewer page is inside a pop-up
or an iframe). (displayProblem.png).

Here is a list of open bugs with Viewer and Compare:

  • Compare always generates the last report page (reported on 29/01/2015)
  • Compare ppt/pptx doesn’t work (reported on 29/01/2015)
  • Compare doesn’t detect differences if they consist
    in image insertions (reported on 29/01/2015)
  • Clearing temp folder of Compare (reported on 21/11/2014)
  • Invalid render of some characters in pdf document (reported on 26/11/2014)
  • Pptx file display is very slow (reported on 25/02/2015)
  • Display of document password protected (reported on 27/02/2015)
  • Operation on a file after a compare (reported on 21/11/2014)
  • Compare and display
    operations are slow (reported on 19/03/2015)

customers complain that opening documents is very slow so, as already asked, we
required an optimization.<o:p></o:p>

Waiting for your feedback.



Thank you for combining all issues with different versions of the Viewer library in one post. We understand that all these issues are very important and should be resolved as fast as possible. and we do all our best to speed up the resolving process. Our product team works on resolving the issues and we will come back to you with fixed version of the library as soon as possible.

Sorry for the inconvenience.


The issues you have found earlier (filed as WEB-1710;WEB-1720) have been fixed in this update.

This message was posted using Notification2Forum from Downloads module by GroupDocsNotifier.



Have you got news about the issues? Our customers begin to get angry.


viewerCode = Viewer.ClientCode()
.Stream(byteStream, fileNameViewer, extension, fileName, true)
.UseHtmlBasedEngine(true, true, false, true) // to improve performances



Thanks for your patience and for using GroupDocs.Viewer.

Our GroupDocs.Viewer product team works on your tasks, but I’m afraid that I don’t have much news about the WEB-1597 issue right now. The issue is with 3d party library and it’s hard to fix the issue without their help. We also are waiting for good news from them, but there is no update for them at this moment.

To do all possible what we can to speed up fixing of the issue, I requested an update from their Enterprise support and I hope I’ll have some news from them soon and we will be able to provide you the ETA of the
WEB-1597 issue.



i downloaded the latest version but still get the errors. Please look at handler declarations on web.config and viewer widget initialization (that i moved in web method and work fine for update document problem) in attached file.



Hi, my boss asks when you can resolve the reported issues. You are causing problems with our customers.


Hello Gianluca,

We have double checked these issues (WEB-1710 and WEB-1720) with the IE9 and all work well for us. The only thing is please check that you use such handlers for your App with the Classic mode of the pool:

Also please try with this example project (it’s your project that you have shared with us earlier). Example of the txt and eml files are added.

Best regards.



We have a good news for you. The issue was fixed in the 3rd party library and they will release it in about 20 days. Then we will be able to resolve it in our library and release fixed version.

We will notify you ASAP when the fixed version will be available.

Thank you.


Hi Pavel,

with tests on new viewer dll i get a lot of “Error: Object doesn’t support property or method ‘replace’” errors and in ie9 a lot of script errors, expecially in iframes.
If possible, can we have a teamviewer session to see it ? Thanks


The problem that you will fix is about the problem of HtmlBasedEngine(false)? Because we can not see what is the bug that you reported in the previuos post.


Hi Gianluca,

Could you please share with me screenshot of the errors, where and when you get them.

Thank you.



Thank you for coming back. No, if to use .UseHtmlBasedEngine(false) all works fine and the document rendered well . This issue is reproducible only with .UseHtmlBasedEngine(true). Since that will be resolved the issue with the HTML mode.

Thank you.

With IE10,

doc file

with ie9

doc file (the same of previous n.1)
txt file
pdf file (after the error it shows correctely)
xslx file


This message was posted using Email2Forum by pavelteplitsky.


So with WEB-1597 issue what do you fix?


Hi Gianluca,

Thank you for the screenshots. If I understand you correct you continue to use iframe for the Viewer integration. Unfortunately the IE browser doesn’t fully support the iframe, it works unstable and can be very “painful” to use it.

As we said earlier we strongly recommend you to not use iframe for Viewer integration.

Please try to use exactly the same approach as shown in the example that we shared with you.

Best regards.



This fix will resolve the issues with document rendering (this one). Also there will be allot of other fixes so you will need to check if the JavaScript issue will happen again - if yes (will happen) please notify us.

Thank you.


Sorry but we can’t avoid the use of iframes because of site structure. So thoses problems haven’t a solution?




With this bug do you also fix the problem with word files that I reported? I noticed that it is a problem of css…