ImageResizer doesn't work with EPiServer 7.5 out of the box, read my blog post for a basic understanding of what to do when using ImageResizer (http://world.episerver.com/Blogs/Andre-Hedberg/Dates/2013/12/Get-ImageResizer-to-play-along-with-EPiServer-75/).

I think the link becomes in that format since you use "Url" as the property type and not "ContentReference". Correct me if I'm wrong. :)

I have managed to make ImageResizer work with our new site :) The behavior of Url property is what concerns me. I think i will try using ContentReference.

Url should still be valid to use with the new Assets system. ContentReference is somewhat preferred from a performance perspective if you do not require additional query string parameters which I assume is the case if you want to use ImageResizer. Url will convert the "public" url to an internal format to handle changes in the URL structure (aka permanent links). When shown on the site, it should convert to the public format together with any custom query string parameters you have added to the URL.

What exactly is your problem? Are the links not converted to the public format on the site or are you loosing query string parameters?

When I add a query string to the Url property, for example using ImageResizer:

<img src='<%= CurrentBlock["ImageUrl"] %>?width=270' />

the image markup becomes:

<img src='/link/2ec8f6c283a14b689f4c79111f315d1b.aspx?id=213&epslanguage=en?width=270' />

which I get an YSOD. It was working before we upgrade the site to 7.5

You could try to convert your permanentlink to a FURL before writing it to output. Something like:

<img src='<%= EPiServer.Web.UrlResolver.Current.GetUrl(CurrentBlock["ImageUrl"]) %>?width=270' />

I actually have no idea why it was working before the release. Adding a query string parameter with a hard coded "?" to a link where you do not have control of the format is always a risc since you do not know if the original link already contains a query string or not. I would either add a better handler to add your additional query string (that is, use a class to modify the URL or at least check if the URL already contains a '?'-character) or use the UrlResolver as Johan suggested.

Thank you. My problem is now resolved.