ex.args only contains a single element which is the full error description. Path names removed and replaced with "<value>".
ERROR 000466: <value> does not match the schema of target <value>
Failed to execute (Append).
As noted previously, I can parse this string to get the error number, but I can remember older versions of Python having an errno value. Ultimately, I want to delete the feature class when this error occurs and create a new version with the modified schema.