Installing the Spyder 5.1.5 library in a cloned Python environment results in new and existing notebooks, and returns the error message "Error: Failed to open notebook."

Additional Information

Workaround

Search for and install the pro-notebook-hotfix package from the Package Manager in ArcGIS Pro.

1. Launch ArcGIS Pro and navigate to the Package Manager.
2. Open Environment Manager (click the gear icon near the top right).
3. Activate the clone.
4. Click the refresh button.
5. Close Environment Manager.
6. Click the Add Packages tab.
7. Search for pro-notebook-hotfix and install the package.

Alternatively, run the following command from the Python Command Prompt to install the hotfix into the active environment:

conda install pro-notebook-hotfix

Steps to Reproduce