Issue:
It is not possible to load the Arnold plugin (mtoa.mll) in the plugin manager in Maya. The plugin may be listed, but clicking in the Loaded or Auto-Load field in the plugin manager does nothing. The error “A dynamic link library (DLL) initialization routine failed.” may appear in Maya.
Solution:
To solve issues at loading the Arnold for Maya plugin, chose from the options:
Reset the Maya user preferences and update Arnold to the latest version
- Close Maya.
- Reset the user preferences by following the steps from this article: How to reset the Maya Preferences to Default.
- Download the latest Arnold for Maya plugin here: Arnold for Maya.
- Start Maya.
- Open the Plugin Manager and search for mtoa.mll plugin.
- Click on Load or Autoload to load the plugin.
- Press Close to confirm and close the plugin manager window.
Uninstall the Arnold MtoA plugin and re-install the software (Windows)
- Uninstall the Arnold plugin from the installation folder of the previous version of MtoA:
- Go to C:\Program Files\Autodesk\Arnold\maya2020
- Execute the file Uninstall.exe to uninstall the program.
- Download and install the latest Arnold for Maya plugin from here: Arnold for Maya.
Note: This example is regarding Maya version 2020. Search for the appropriate version that you are using.
- Use the Add/Remove programs function in Windows:
- Click on the Windows Icon.
- Type Add or Remove.
- Click on Add or Remove programs.
- In the Apps and features window, search for MtoA.
- Uninstall the program.
- Download and install the latest Arnold for Maya plugin from here: Arnold for Maya.
Perform a Clean uninstall of Maya
- Follow the guide to completion: Perform a clean uninstall | Download & Install | Autodesk Knowledge Network
Source: https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Can-t-load-the-Arnold-plugin-in-Maya.html?us_oa=dotcom-us&us_si=e1c6dff8-02cf-4063-a7dc-1cf89b8550d5&us_st=Arnold