Dropbox invalid redirect_uri, must be an absolute uri

Digging in a bit deeper and looking at this code fragment:

this._oauth2State = Guid.NewGuid ().ToString ("N");
				var authorizeUri = DropboxOAuth2Helper.GetAuthorizeUri (OAuthResponseType.Token, DropboxAppKey, RedirectUri, this._oauth2State, false, false, null, true); //force re-authenticate
				var webView = new WebView { Source = new UrlWebViewSource { Url = authorizeUri.AbsoluteUri } };
				webView.Navigating += async (sender, e) => {
					if (!e.Url.StartsWith (RedirectUri, StringComparison.OrdinalIgnoreCase)) {
						// we need to ignore all navigation that isn't to the redirect uri.
						return;
					

the e.Url used to match the RedirectUri, and now it doesn't. Instead, the e.Url now contains the RedirectUri as a query string parameter as follows:

https://www.dropbox.com/oauth2/authorize?response_type=token&client_id=<hidden>&redirect_uri=<encoded_redirect_uri>&state=7396a67d6c604d45899fd5c588877d1f&force_reauthentication=true

Is there something more that I am missing?

Another note: the code is based on https://gist.github.com/tomcrusader/b0856a383bcdcf905c7a774c8c1b0879 -- and it used to work fine.

Seems like there were some issues with the new Xamarin Forms upgrade, .net and PCL stuff, so I rolled back all packages upgrades including Dropbox and now things are working.

@xtremebytes I ran into the exact same issue.

My investigations:

Just downgrading to Xamarin.Forms 2.5.1 resolved the issue for me. I kept the newer version of the dropbox sdk and the .NET standard stuff. The issue only exists on iOS, Android and UWP still work fine without downgrading.

So it seems the problem occured in the Xamarin.Forms iOS stack while switching from Forms 2.5.1 to 3.0 or 3.1-Pre1.

Otti Thanks a lot for confirming this.