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Watermark Text Size Issue with PDF in Viewer API using C#

Hi All,

I am trying to set the size of the text while generating pdf document through Viewer API with the help of WaterMark API of GroupDocs.Viewer.Options namespace. I am trying to set the watermark size with the help of following code

string footerwaterMark =  "This document is licensed to Admin User at MET and its usage is limited to school year";

Watermark objWaterMark = new Watermark(footerwaterMark);
objWaterMark.FontName = "Calibri";
objWaterMark.Size = new Size(30);

Now when I am trying to open this pdf file through Adobe Reader it is giving me following error :-
image.png (10.9 KB)

If I truncate the content of this text till “This document is licensed to Admin User at” and size as half of the page size with help of code

objWaterMark.Size = Size.HalfSize it is working and giving me the output as

image.png (6.8 KB)

But any change in combination of the size and text is always giving me the error for which I am unable to figure out the reason. Currently for development I am using evaluation version of Group Docs, if this issue might be related to licensing as well, please help


We have reproduced this issue the issue ID in our internal bug-tracker is VIEWERNET-3453. At the moment we have found that the issue is not related to licensing. You’ll be notified in case of any updates.


We have found that this issue can be reproduced when the app is targeting .NET Core. Could you please confirm that you’re targeting .NET Core in your app?

@vladimir.litvinchik :- Thanks for your update. Yes, We are using .NET Core for the development.

Kindly update me once its done.



Sure, the issue is under investigation now. We’ll update you in case we have any new information.


GroupDocs.Viewer for .NET v21.11 that includes fix for this issue has been published. You can find the new version at

Have a nice day!