Error converting object (string) to Int32: TypeError: object cannot be converted to an IntegerDtype

It's known bug, as explained here.

Workaround is to convert column first to float and than to Int32:

df.column = df.column.astype('float')  # first convert to float before int
df.column = df.column.astype('Int32')

or simpler:

 df.column = df.column.astype('float').astype('Int32')

Make sure you also strip your column from whitspaces before you do conversion:

df.column = df.column.str.strip()