Use Kindle Previewer to detect EPUB errors and send to kindle

I like to send EPUB files to my Kindle or the Kindle app on my mobile phone to read. However, recently when I tried to send an EPUB file, I received an email with the subject line: “There was a problem with the document(s) you sent to Kindle,” but no details were given about the error.

Initially, I thought the issue was with the content of the EPUB file. Therefore, I tried to extract the file and edit the content. Then, I created a new EPUB file, but it still failed to send to my Kindle.

After researching online, I found a solution: using Kindle Previewer to check the EPUB file. I installed the application and opened the EPUB file with Kindle Previewer. It detected the errors in the file, which I fixed. Once I sent the updated EPUB file to my Kindle, it was successfully delivered.