Invalid File Format on my Apple Pages file

We are not clairvoyant about what "Invalid File Format" means in the context of your environment.

Questions

1. What version of Pages are you using on Sequoia, and have you made changes to this document in an older version of Pages on a different Mac with older operating system?
2. Where have you been saving this document, and where last was it saved before the above error?
3. Is there a backup copy of that document to be found elsewhere?
   1. If you emailed it as an attachment, does that attachment still exist in your Mail Account Sent folder?
4. Have you single-clicked on this "Invalid File Format" document and pressed the option+cmd+i keys to present a Get Info panel? Is the Kind shown as Pages? Is the file size = 0?

"Invalid File Format on my Apple Pages file: I was using Apple Pages on my 2019 MacBook Pro. I had been writing a book for 3 years and just finished the book and was just updating the font. 10 minutes later I attempted to sign into my Mac and pull up my file in Apple Pages and I received the statement, 'Invalid File Format'. I now have the newer version of Apple Pages but unfortunately I cannot access any of my work because Apple continues to say, 'Invalid File Format'. Is there anyway I can correct the file format so that I can access my 3 years of work?"

-------

"Invalid File Format" in Apple Pages:

So, what's the File Format(s) you have on these files giving you this issue.

1. Right Click: on the icon
2. Select: Get Info
3. Expand: General
4. View: Kind

Star with an Update:

Keep your Mac Up-to-Date: So that files open without issue, it is best to keep your Mac up-to-date with he most recent compatible version.

Create a Time Machine Backup:

Important: Prior to the update installation, create a Time Machine Backup of your Mac, so that you can have something to restore your Mac from, should anything go wrong, during or after the install.

Updating your Mac:

1. Go to: Apple menu: 
2. Click: System Settings
3. Click: General
4. Click: Software Update
5. Click: Check for Updates

"I was using Apple Pages and the file is saved as a Pages document.: the information you provided as far as saving document with Time Machine is only good advice for future documents and does not help me recover my existing document. You did not provide any solutions to try and recover my existing document so this was not helpful."

-------

'Invalid File Format'. In Notes App:

A. See this Google Search Query: 'Invalid File Format' "apple pages" site:discussions.apple.com

B. VikingOSX mentions lots on this. It's a damaged file, and may not be recoverable again. If you were saving these to one location on iCloud, and sharing it with other Apple Account, it will become broken, meaning the file cannot be accessed anymore. If you have this accessible on the older Mac, you might want to right-click on it, and then compress the file. It would be as a ZIP file, thereby keeping it entailed as a file of its own within a file. Essentially, compressing it would keep it safe. So, if you do't have these on a Time Machine Backup, then you likely just can’t recover it. "vulnerableness" and "broken" are the keywords you find in relevance to handling of these files.

Hello!

Was the backup created?

Can you tell us what kind of procedure and where and what difficulties you have encountered?

Sincerely,