File upload errors are due to formatting issues within the file.
If you are uploading an ePub, please run the file through an ePub validator (e.g. ePub Checker) and correct any errors that appear prior to re-uploading.
If you are uploading a file in a different format, please ensure that your file is consistent with our conversion guidelines prior to re-uploading.
If you're receiving a non-critical error, this won't prevent your book from being published. These errors also won't affect how a reader views the file. The reason we let you know they're there is because they may prevent a partner site from ingesting the file. However, to publish on Kobo alone, no action is needed.
If you have any questions about the error you're receiving, please get in touch with us by clicking the Submit a request button above.