The column after "A" is "" that means it's empty so SSIS takes empty space as string.

You are getting error because your destination column is Integer.

You need to convert empty space into NULL

Use derive column and in that change empty space into NULL

for example Write expression in derived column

[ColumnName] == " " ? (NULL, DT_WSTR,20) : [ColumnName]

This will convert " " into NULL. and you can process your file.

Please let me know If you still get that error.I had the same issue and I resolve it.