Lost hyperlinks, hyperlinks link to wrong place, hyperlinks stop working

Problem

Your presentation contains a lot of hyperlinks and suddenly you find that some of the links stop working. Either they link to the wrong place or don't work at all.

Solution

If links to some slides don't work but links to others do, look for commas in the slide titles. Because of the way PowerPoint stores link information, commas confuse it and make the links break. Remove the commas from the slide title and all will be well.

If your links take you unexpectedly to pages on the internet or cause PowerPoint to try to connect to the net, see Links between slides don't work in PowerPoint HTML

Avoid creating presentations with too many links in the first place.

Instead, create multiple linked presentations. See the linking tutorial at MVP TAJ Simmons' Awesome - PowerPoint Backgrounds.

Once links start to break, try deleting some of the slides that contain the broken links and/or break up the presentation into several smaller ones (see above).

It can also help to export the presentation to HTML then "round-trip" it back into PowerPoint by opening the resulting HTML.

Problem

According to this Microsoft article:

PowerPoint stores the hyperlink information in the Document Summary storage area of the presentation. This storage area has a limit of 64 KB. The Document Summary storage contains all the document properties, custom properties, references, and other similar data.

Because the Document Summary storage is used by different aspects of the presentation, there is a finite number of hyperlinks that can be stored in presentation. This is compounded by the fact that the longer the text is for a hyperlink that you have to store, the fewer you can store.

Theoretically you can store upward of 32 KB of characters in the Document Summary, which translates to approximately 6,500 words. More than half of this is already allocated to dedicated Document Summary items. After the free space is used, no more can be allocated to the presentation.

The reference to "words" is misleading. Are both of these "words":

This: word
And this: http://deep.deeper.deepest.domain.com/folder/after/folder/after/folder/and/finally/ThisInsanelyLongFilenameThatsTotallyOverTheTop.htm?fFollowedByMilesOfQueryParametersThatOnlyASickoCouldLove"

Forget the words. Count the characters, 'cause it's the characters/bytes that count.

At any rate, it all suggests that there can be no more than 32k *max* worth of hyperlinks, at least in some versions of PowerPoint. And apparently some of that might get eaten up by unspecified other things. We've seen hyperlinks go sour in presentations with 20kb worth of links or less.

MS says that this problem no longer occurs with links you create to sites external to the presentation in PowerPoint 2002 and 2003.
MS acknowledges that it's still a problem for internal links.

The free PPTools FixLinks demo will give you a report on the links in your presentation and a general idea of how much space your existing links use. As a general rule, we'd suggest caution if it reports more than 15,000 bytes worth of links.

PowerPoint MVP Bill Dilworth has a clever workaround that relies on VBA but allows you to have an unlimited number of hyperlinks. See his Unlimited Links macro