I'm really just posting this so at least there's one relevant hit if anyone googles for it.
We use query parameters in links from our main website that point to portal pages that are protected by login. E.g. https://someportal.whateverdomain.com/buyaproduct/?productid=12345
The portal is configured to use Azure AD B2C for sign-in / sign-up and if a user is not yet authenticated then the portal redirects the user to B2C to login because the buyaproduct page is only accessible to signed-in users. On completion of sign-in, the user should be at the buyaproduct page looking at product 12345.
Up until about the start of February, this was all working finely and the productid was passed through the B2C login (in the state property, if I recall correctly).
However, it seems a portal update (to 9.3.ish) in early February broke this and the parameter is now lost through the B2C process. [I can see it's a portal and not a B2C problem because checking in the Chrome debugger I can see there is a redirect to a portal-based ExternalLogin URL first and the parameter is contained in that but incorrectly URL encoded.]
Anyway: couldn't find a workaround, it's been raised with Microsoft Support and we await some useful progress.
Cheers,
Mike.
