topic Re: Running Python Scripts from Add-In and Stand-alone Python Environments in ArcGIS Pro SDK Questions

Running Python Scripts from Add-In and Stand-alone Python Environments

Vidar — Wed, 14 May 2025 15:30:52 GMT

Hi,

I’m hoping to get some insight or advice from the community on an issue we’re encountering with a custom ArcGIS Pro Add-in developed in C#.

Software Stack:

ArcGIS Pro 3.2.4 (Advanced + Spatial Analyst)
Windows 10 Pro (Build 19045.5737)
Visual Studio 2022 (v17.13.6)
Python environments: arcgispro-py3 (default) and a separate standalone Python 3.9 installation (required for pygplates)

Objective
We have a custom Add-in button that runs two Python scripts in sequence:
1. Script 1 runs using the ArcGIS Pro environment (propy.bat).
2. Script 2 runs in an external standalone Python 3.9 environment (due to dependency conflicts with pygplates).
3. Script 1 runs again for some arcpy based clean up and other misc stuff.
  This all works well until the user manually adds a raster to the map (via Map → Add Data → Data). After doing this, the second script fails when executed via the standalone environment. This is not the only thing that causes this problem - if the user opens up the interactive Python prompt in Pro - that causes the same issue.
  Symptoms
  After adding a raster in the Pro UI, attempts to run the tool again affects the external Python script fail with errors like:
```
Fatal Python error: init_import_site: Failed to import the site module ... TypeError: type 'types.GenericAlias' is not an acceptable base type
```
  If we run the same scripts from a standalone .NET Console app (i.e., not from within Pro), the scripts work perfectly, so I know it's nothing to do with scripts themselves. The same scripts also work perfectly if run within a Python Toolbox - its only if the scripts are triggered from C# using the System.Diagnostics.Process instance.
  See code example below:

public static string RunPythonScript(string scriptFileName, string[] scriptArguments, string pythonPath) { string scriptPath = Path.Combine(@"D:\Projects\FooProject\PythonScripts", scriptFileName); if (!File.Exists(scriptPath)) return "Python script not found."; if (string.IsNullOrWhiteSpace(pythonPath)) pythonPath = GetPythonPath(); if (string.IsNullOrWhiteSpace(pythonPath)) return "Python environment not found."; var args = new StringBuilder($"\"{scriptPath}\""); if (scriptArguments != null) { foreach (var arg in scriptArguments) args.Append($" \"{arg}\""); } var startInfo = new ProcessStartInfo { FileName = pythonPath, Arguments = args.ToString(), UseShellExecute = false, RedirectStandardOutput = true, CreateNoWindow = true }; using var process = new Process { StartInfo = startInfo }; process.Start(); string output = process.StandardOutput.ReadToEnd(); process.WaitForExit(); return output; }

Question to the Community

Has anyone else encountered issues with the Pro environment interfering with external Python script execution from within a C# Add-in?

Is there a known workaround for running Python scripts in multiple environments from a Pro Add-in?
Could Pro be “locking” or initializing some internal Python state that affects subprocesses? I appreciate this will probably be something to do with Conda and the internally installed Python environment Pro installs.
Is there a recommended pattern for isolating or sandboxing these environments in a Pro-based C# add-in workflow?
Why It Matters
Our workflow depends on Python packages that cannot be installed in the default ArcGIS Pro environment (e.g., pygplates). Being able to reliably switch environments from a Pro Add-in is essential for our tool to function correctly and do the calculations we need to do with pygplates. Currently, interaction with the native Pro UI (like adding rasters) breaks that workflow and puts pro into some locked state with the default Python environment.
Would appreciate any insights, workarounds, or confirmation if others have seen similar behavior.
Thanks in advance!

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

RichardDaniels — Thu, 15 May 2025 15:50:40 GMT

ArcGIS Pro supports different python containers (see DeepLearning with ArcGIS Pro discussions re: cloned environment of ArcGIS Pro's default environment,). The scripts would need to be explicitly told what container they should run in. Sounds like when you load a Raster the Spatial Analyst extension is being, for lack of a better word, Turned-On. This is (re)setting the _conda_ python path back to the default used by SA.

See - Install and Setup | ArcGIS API for Python

*By default, ArcGIS Pro has a single conda environment, arcgispro-py3, which includes all Python libraries used by ArcGIS Pro as well as several others, such as scipy and pandas. Enviornments can be activated in Pro via File | Package Manager. I don't know how to do this in C#, but you need to replicate this Activated logic to swith between your Python scripts.

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Vidar — Thu, 15 May 2025 20:28:33 GMT

Hi Richard, thanks for the answer - I will research the first part of your reply. However I think programmatically activating environments in Pro - would be problematic (even if its possible) as you have to restart Pro which would obviously disrupt the user experience and render the add-in unusable.

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

GhislainPrince — Thu, 15 May 2025 22:33:25 GMT

Hi Vidar,

could you try to modify your code to have `ProcessStartInfo` with `UseShellExecute=True` . Just curious if that has positive impact.

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Vidar — Mon, 19 May 2025 09:14:08 GMT

I will have a try - when I've uncorrupted my python environments with Pro. 😞

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Vidar — Wed, 28 May 2025 09:52:16 GMT

HI - Yes I did try this but it didn't help - however I have changed tack and have worked how to leverage using a python toolbox from c# - and that seems to work much better.

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

DanWalters — Tue, 16 Dec 2025 19:34:16 GMT

Did you ever find a solution to this? I have the same problem, and also found it was triggered by (in my case programmatically) adding a raster layer.

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Vidar — Wed, 17 Dec 2025 11:28:54 GMT

I recommend running any python as a python toolbox and calling into your standalone python environments from there - but kick off the python toolbox using ExecuteToolAsync https://pro.arcgis.com/en/pro-app/latest/sdk/api-reference/topic9383.html

This solved all my troubles. Yes you may have to redesign some of your code around a python toolbox - but it is better than using the Process command in C#. This is the only solution I found to this problem.

topic Re: Running Python Scripts from Add-In and Stand-alone Python Environments in ArcGIS Pro SDK Questions

Running Python Scripts from Add-In and Stand-alone Python Environments

Symptoms

Question to the Community

Why It Matters

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Re: Running Python Scripts from Add-In and Stand-alone Python Environments

Re: Running Python Scripts from Add-In and Stand-alone Python Environments