Bug: Installing or updating the ArcGIS Python package causes ArcGIS Pro 1.4.1 to crash
After installing the ArcGIS Python package, ArcGIS Pro crashes when trying to use the Python window, or sometimes when opening a project.
There have been some reports of Pro 1.4.1 crashing after packages which depend on the Jupyter/pyQT packages are installed via Conda. This is due to a problematic DLL that shipped with Conda that doesn't meet PEP 384.
It is easy to fix, simply delete or rename the culprit DLL in the active Pro environment's folder. In the %ProInstalDir%/bin/Python/envs/arcgispro-py3 folder (or equivalent, if additional environments have been created), delete or rename Python3.dll.
Many people are hesitant to alter DLL files, but in the same folder is Python35.dll - this is the one which should be loading and fixes the issue. Once Python3.dll has been removed, reopen Pro and it should work as expected. This issue has been identified and fixed for Pro 2.0.