Could not copy "\packages\PdfiumViewer.Native.x86_64.v8-xfa.2017.12.4.236\build\x64\pdfium.dll" to "bin\x64\pdfium.dll". Exceeded retry count of 10. Failed.

[victor-mikhalev]

I have found the issue in MsBuild scripts. When package added to the WebSite project then IIS locking file bin\x64\pdfium.dll.

Build script tries each build copy pdfium.dll.

To resolve this issue you need to change:
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
to
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>

in PdfiumViewer.Native.*.props files

[bryjamus]

I confirm this behavior. When I changed to:
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
Compilation has no warnings.
Is it possible to change this property or where can I find those props files to creatr PR for this issue?