How to export a 500+ pages of interactive PDF from indesign ?

There can be multiple reasons for this.

Option 1

You could firstly try:

File>Export and choose IDML - and open the newly saved file.

Resave your InDesign file now as a different file name (version number if you like)

See if it exports.

Option 2

If that's not working then you'll need to track down the issue:

On a backup of your current file try this:

Divide and conquer.

Try exporting pages 1-250

And if that exports fine - then try 251-500

Whatever side it fails on is where the issue is.

If it fails on 251-500 then try exporting pages 251-374

And eventually you will be down to a page that is causing the issue.

You can then see if there's something on that page - an image or a text frame that needs to be updated.

That would mean - reimport the image - or rebuild the text frame.

You can know which one it is by deleting half the page items and exporting the page - then try deleting more items.

How much RAM and spare hard disk capacity do you have?
What kind of interactivity does the document have?

Have you tried the Interactive PDF preset?