Versions used: Sitecore Experience Platform 9.0 rev. 171219 (9.0 Update-1).
After reading Kam’s post about changes needed to serve media library items via Azure’s CDN, I implemented a custom Media Provider to append the last modified date to the media URL -so we don’t need to purge URLs on azure when a media item is modified. Then a colleague pointed out Sitecore provides a setting
Media.AlwaysAppendRevision that does exactly this (but with revision number instead).
Unfortunately, this setting breaks the default Media Provider. An
[FormatException: Unrecognized Guid format.] error if shown if you try to add a language version to a media item.
Sitecore has released an official patch to fix the see. Grab it from here
Please let me know what you think and/or if you can spot any errors.