Avoid Changes to Formating of Downloaded File
In order to avoid errors during the ulpload of your adgroups' Target ACoS, please make sure not to change anything about the file except from entering the Target ACoS for your adgroups.
This means, for example, not deleting any tab in the file (eg. the Instructions tab), adding adgroups that were not within the download file or changing the file format (.CSV).
It is not necessary to enter any break-even ACoS - these are populated to the file automatically, if available, to help you decide on a target ACoS.