Recently, I developed a problem in my ArcGIS Pro 2.6 clone environment and had to re-clone. I then added Spyder 4.1.3 with conda to that env and was getting a strange error when using the Run button (green arrow) to run a script:
TypeError: handle_get_file_code() got an unexpected keyword argument 'save_all'
A quick google search presented a solution of :
conda install spyder=4.1.5
Which ironically I had already tried but anaconda choked telling me that it couldn't find the package in all the searched channels.
Bottom line, if you get that error, upgrade. If the upgrade chokes, try it again later....