This error arrived after replacing the design of an R4 database with an R4 Template stored on an R5 server.

I think this was because the Abotu page was being updated as well.

This is an option on the Properties of the about page.

In R5 the about page is stored differently than an R4 database.

In R4 the document ID is always the same.

To fix this problem I merely opened the About page from the R4 design client and

resaved it.