Fix EPUB “Processing” Error in Google Play Books Using Calibre

Google Play Books is a solid way to keep your ebook collection synced across devices—but sometimes it refuses to upload an EPUB and gets stuck on “Processing…” forever. No error message, no hint, nothing.

The good news: you can usually fix this yourself in a few minutes using Calibre, the free and powerful ebook management tool.

Below is a simple, reliable process to repair your EPUB so Google Play Books accepts it without complaint.

Why Google Play Books Gets Stuck on “Processing”

When Play Books can’t finish processing an upload, it usually points to one of these problems inside the EPUB file:

Corrupted internal structure
Invalid HTML/CSS
Missing metadata
Embedded fonts or images that trigger validation issues
EPUB generated by tools that bend (or break) EPUB standards

Calibre can fix most of these issues automatically.

Step 1: Install Calibre

If you don’t already have it:

Download Calibre from the official site
Install it on your computer (Windows, macOS, or Linux)

This is the only tool you’ll need.

Step 2: Import the Problem EPUB Into Calibre

Open Calibre → click “Add Books” → choose the EPUB that won’t upload to Google Play Books.

Once it’s in your library, you’re ready to repair it.

Step 3: Convert EPUB → EPUB

This may sound strange, but converting an EPUB back into EPUB is one of the fastest ways to fix internal errors.

Select the book
Click “Convert Books”
Set both Input and Output formats to EPUB
Click OK

Calibre rebuilds the file and cleans out structural issues in the process.

This alone fixes the majority of stuck-processing errors.

Step 4: Check Metadata (Optional but Helpful)

Bad metadata sometimes triggers Play Books issues. While you’re still in the conversion window:

Click “Metadata”
Make sure the title and author are filled in
Remove strange characters or formatting

Clean metadata = fewer upload problems.

Step 5: Save the New EPUB

After conversion, right-click the book → “Save to Disk” → choose a folder.

This exports the repaired EPUB.

Step 6: Upload the Repaired EPUB to Google Play Books

Now open Google Play Books → Upload files → pick the new EPUB.

In most cases, it processes within seconds.

Bonus Fix: Disable or Strip Embedded Fonts

If your book still won’t upload, the culprit is often embedded fonts.

In Calibre:

Open Convert Books
Go to the “EPUB Output” section
Check “Remove embedded fonts”
Reconvert your EPUB

Try uploading again. This solves stubborn cases.

When You Should Rebuild the EPUB Completely

If nothing above works, the EPUB is likely deeply corrupted.

Your options:

Convert the EPUB to AZW3 or MOBI, then convert back to EPUB
Or extract the EPUB, fix/replace the HTML files, and rebuild (advanced)
Or find a fresh source file

Most users never need these steps, but they’re there if you’re dealing with a badly formatted ebook.

Final Thoughts

The “Processing…” freeze in Google Play Books is annoying but fixable. Calibre does the heavy lifting by cleaning up the EPUB’s structure, rebuilding it, and removing the quirks that Play Books rejects without explanation.

In short:

Calibre + EPUB→EPUB reconversion = fast fix

Mark Vincent

Tech enthusiast and content creator passionate about making technology simple for everyone. I share practical tips, guides, and reviews on the latest in computers, software, and gadgets. Let’s explore the digital world together!