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UseHtmlBasedEngine generating resource not found error



we are using groupdocs.Viewer( for application and we recently migrate the application from IE8 to IE11 but we are facing performance issue after IE9 version.

earlier we are using image based rendering but that is very slow when using in IE11 and document size is big(more than 5 MB).
so we introduce html based rendering method but this is generating “The resource not found” error each time we traverse the document.

the setting of groupdocs viewer is :

.UseHtmlBasedEngine(true) // newly added but generating error

on code behind file the cache is defined as :
DocumentCache cache = new DocumentCache(Server.MapPath("~/License/GroupDocsViewer.lic"), “~/Cache/”);

Please suggest all possible way in details to improve the performance of Viewer in IE11.
Thanks in advance



We are sorry to hear that you have such issue. We have tried to reproduce your issue but unfortunately we can’t. Since that to be able to reproduce it and help you to resolve it we will need next:
1. Full code of the web page
2. Full code of the code behind
3. Global.asax.cs
4. Web.config
5. Document example (and include full path of where it stored)

Or you can share with us example of your project and we will fix it for you.

Also we attached code example of how to use HTML rendering mode and stream.

As for the how to speed up the Viewer - Please download latest version of the Viewer . By default, when you open a web-page with GroupDocs.Viewer widget, and the target document is invoked (for displaying), on the server-side GroupDocs.Viewer converts the document to the images and text (for the image-based rendering) or to the HTML, images, fonts, and CSS (for the HTML-based rendering). Only when this conversion process is finished, GroupDocs.Viewer begins to transmit data to the client-side and end-user can see content of the document in the browser. That’s why it takes so much time - GroupDocs.Viewer needs to convert all document, and they are really big. The conversion speed depends on the performance of the server - CPU, memory, storage.

However, there is a “PreloadPagesCount” method. When using it, for example, “.PreloadPagesCount(1)”, GroupDocs.Viewer begins to transmit data to the client-side when only first page of the document is converted. After applying this method to the 1st document (17 MiB), GroupDocs.Viewer shows its first page almost instantly. All other pages are shown on demand, when you try to open them.

There are some other methods to increase performance:
1. Try to use HTML-based rendering mode (“UseHtmlBasedEngine(true)” method) if it is suitable for you and there are no document distortions.
2. Use “PreloadPagesCount(1)” method. When using this method GroupDocs.Viewer will begin to load document to the client-side when first page of the document will be converted. When this method is not used, GroupDocs.Viewer converts all pages of a document and only then sends it to the client-side.
3. Use “MinimumImageWidth(value)” method. MinimumImageWidth: if set, the Viewer will load page images with the specified width from the server when starting. It will not load page images from the server again after zooming if the current page image size is smaller than the value specified and if the original (not scaled) page image size is smaller than the value specified. It means that in most cases the GroupDocs.Viewer will load page images only once and will not reload them after zooming in/out.
4. If this is possible for your business-logic, disable thumbnails (“ShowThumbnails(false)”).
5. If this is possible for your business-logic, disable ability to select text by using “SupportTextSelection(false)” method.
6. Use “ShowViewerStyleControl(false)” method - it will disable “double page flip” option and will increase performance.

Best regards.



Thank you for your valuable guidelines. this helped us in successfully implementing the HTML based rendering technic.
Although now we are getting error as “A mandatory parameter is not found. Parameter Name: embedImagesIntoHtmlForWordFiles” each time a PPT files open.
We have not encounter such type of error when using Imagebased rendering technic.

Suggest some possible way to resolve this issue.


Hello Puneet,

Glad to hear that you was able to use HTML rendering mode with your stream.

As for the new issue - please share with use the ppt file with which you have this issue and the .aspx and aspx.cs files that we can check your code and reproduce the issue.

Best regards.