"Notebook not found at requested URL" when attempting to open a Jupyter Notebook

Error Message

In ArcGIS Pro, attempting to open a Jupyter Notebook returns the following error message:

"Notebook not found at the requested URL. This may be caused by an unsupported proxy configuration, or an invalid Jupyter Notebook server configuration."

This issue is often accompanied by the immediate failure of Python-based geoprocessing tools, such as Raster Calculator or Feature Class to Geodatabase. When these tools run, they return a traceback error indicating "Permission denied" for specific .py files. These symptoms indicate that the Python environment is broken due to restricted access to the installation directory.

Cause

This issue may originate from modified or updated permissions of the ArcGIS Pro installation directory, typically C:\Program Files\ArcGIS. These changes are often a residual effect of third-party applications or Python distributions, such as Anaconda, installed on the same machine, which can overwrite default folder access and inheritance. When these permissions are restricted, ArcGIS Pro is unable to properly initialize the Jupyter server or access the Python executables required to run script tools.

Solution or Workaround

Note:
The following steps involve modifying system-level folder permissions. It is recommended to perform these steps under the guidance of your IT Department or with the assistance of a system administrator.

To resolve this issue, the folder permissions for the ArcGIS Pro installation directory must be reset to inherit default system permissions.

1. Close all ArcGIS applications and ensure no ArcGIS-related processes are running in the Task Manager.
2. Open File Explorer and navigate to C:\Program Files.
3. Right-click the ArcGIS folder and select Properties.
4. Navigate to the Security tab and click Advanced.

5. In the Advanced Security Settings window, click Change Permissions. Administrative privileges are required.

6. Check the box at the bottom labeled "Replace all child object permission entries with inheritable permission entries from this object".

7. Click Apply. A Windows Security dialog box appears with the following message:

"This will replace explicitly defined permissions on all descendants of this object with inheritable permissions from ArcGIS. Do you wish to continue?"

8. Click Yes.
9. Once the permissions are reset, click OK to close the Advanced Security Settings window.
10. Click OK to close the Properties window.
11. Launch ArcGIS Pro and verify that the Jupyter Notebook opens correctly and that script tools run without permission errors.

Note:
If the environment does not contain third-party Python distributions or environments, please refer to the following documentation for alternative causes related to proxy and network configurations: Error: ArcGIS Notebooks: Notebook Not Found at the Requested URL