We recommend that you run the epubcheck validation tool on your files before distribution, to ensure that there are no errors. You can run the standard EPUBCheck validation tool right from your project Dashboard.
Scroll down to find the menu labeled “Validate you files” and click to expand it.
Click the “Validate with EPUBCheck” button, and wait for the validation to finish.
The EPUBCheck results will be printed right there on your Dashboard, along with the book metadata that EPUBCheck detected in your file. This report will disappear when you close the menu option, but you can re-run it at any time.
If there are any validation errors, let us know and we can help you troubleshoot solutions: firstname.lastname@example.org