IronCefSubprocess is a small binary file deployed with IronPDF's Chrome renderer that allows true multi-process multi-threading. It is an integral and non-optional part of the Chromium browser's architecture.

IronCefSubprocess is often located at /bin/runtimes/*/native/IronCefSubprocess

Fixing Execute Permission to IronCefSubprocess

  • chmod: changing permissions of 'IronCefSubprocess': Operation not permitted
  • Error while loading vcruntime140_1 library from path

An uncommon but frustrating error is if IronCefSubprocess is not executable. This is a file permissions issue that may have to be manually resolved in rare cases, particularly on higher security Linux distributions.


Browse to IronCefSubprocess in Explorer as an Administrator. Right click and give the .NET Runtime permissions to Read and Execute manually.

macOS and Linux

You can use shell command such as _chmod _and _chown _or setfacl to change permissions to IronCefSubprocess.

Which user profile does .NET use to execute IronCefSubprocess?

  • The user profile which .NET Runtime uses to execute code can be discovered using the .NET System.Environment.UserName property.
  • The .NET runtime's username will also be reported in any Exception messages thrown by IronPDF relating to this issue.

Fixing A Missing IronCefSubprocess File

In the case of a missing IronCefSubprocess file.

Ensure you have added NuGet references to the IronPdf.Native.Chrome packages for your target platform.

Common references are:

IronPdf.Native.Chrome.Windows IronPdf.Native.Chrome.Linux IronPdf.Native.Chrome.MacOS

Next, rebuild your Visual Studio solution, and publish your project for the correct deployment platform (AKA RuntimeIdentifier).

Ensure that the runtimes folder is present, and contains all the files contained in your development environment.