Hi,
Some alert messages in iBooks include the phrase "text not allowed." For example, you might see "ERROR ITMS-9000: 'FileName.html(16): text not allowed here.'"
You can include text only in certain elements of an ePub, such as the paragraph element (<p>) or header element (<h1>). You might also see this error if you use the blockquote (<blockquote>) element in the book’s metadata.
Go to the iBooks Asset Guide in Resources and Help in iTunes Connect to learn how to code using ePub best practices.
Information above is from this support article > If you see a "text not allowed" message in iBooks - Apple Support