ChemDraw 19.0 gives " An unexpected error occurred (#-50)" message when opening files created with previous versions.
This issue appears when the symbol "µ” is present in the document, mostly in the Stoichiometry Grid. You can open the file in ChemDraw 18.2 and other previous versions, but it crashes when you open them in ChemDraw 19.0.
The current workaround is to roll back to version 18.2.
Update: You can now download version 19.1 from the download portal to correct his behavior.