Magnolia 4.5.17 seems to break the shop product detail page of the Magnolia Shop Module. Shop product detail URLs such as in our Worldsteel Shop: http://localhost:8080/magnoliaAuthor/internet/publications/bookshop/product-details.~Map-of-China-steel-mills~PRODUCT~Map1~.html now result in a 404 error page (nothing in the logs).

Backporting to Magnolia 4.5.16 solves the issue.

It must be something in the Magnolia 4.5.17 changelog that causes this. Could you please look into this? Of course we do want to upgrade to 4.5.17 (and future releases).

In any case I don't think the product detail URLs are particularly nice. '~' symbols in URLs are not common practice and are in fact not officially supported (but do work I guess..):

From the RFC 1738 specification:

Thus, only alphanumerics, the special characters "$-_.+!*'(),", and reserved characters used for their reserved purposes may be used unencoded within a URL.

The most SEO and user friendly solution would be something like:
http://localhost:8080/magnoliaAuthor/internet/publications/bookshop/product-details/map-of-china-steel-mills.html

but that would be a bit harder to implement I guess. And this would only work when shop product names are unique (which they are not currently). Not a bad thing I think. Alternatively the unique product UUID could be used.

PS: I have not tested it on a clean Magnolia 4.5.17 with Shop Module and demo project yet.