In a VS 2017 Winforms VB application dealing with package designs, predominatly based on PDF files, I felt the need to provide a preview of those files in several points along the workflow.
At first I used a third-party component, but in some cases the designers created one or more hidden layers in the PDF files and they were all made visble by the component, obviously creating some confusion.
In the begining of April I decided to use the Adobe ActiveX control instead, with good results since then ( AcroPDF.dll, which in my Windows 10 machine the Acrobat Reader DC installer placed in C:\Program Files (x86)\Common Files\Adobe\Acrobat\ActiveX ).
However, yesterday I had to make a slight change in a form ( not related with PDF files ), deployed the application, and a few hours later some users reported an exception in several forms using the PDF viewer ( "Could not load file or assembly 'AxInterop.AcroPDFLib', Version=1.0.0.0, Culture=neutral"... ).
At first I thought I could have inadvertently modified the list of deployed files, but both AxInterop.AcroPDFLib.dll.deploy and Interop.AcroPDFLib.dll.deploy were included, and besides I had no problems with the PDF viewer in my computer.
The only significant note I can remember is that there was an apparently large security update of Acrobat Reader DC a few days earlier ( and at least two or three VS updates since the last time I had to deploy a new version of my application ). Besides that, the customer's computers run Windows 8, but I until now it didn't seem to matter.
An extensive Google search on the issue failed to provide any clue, so at this point I can't even identify the source of the problem, much less a solution for it.
Does anybody know what might be going on ?
Thanks.