It appears that some Windows Insiders are running into an error — specifically referred to as error 80242006 — when trying to install the latest Windows 10 Mobile Fast ring build 14955. You may also just see it as "no update available". Thankfully, there's a quick and dirty workaround that should get things back into shape and allow you to install the latest build.
As posted by a Microsoft support engineer on the answers forum, error 80242006 can be circumvented via the following steps:
- Switch your device to the Slow ring
- Change device date to 7 days in the future
- Check for updates (should say "no updates available")
- Change device date back to current date
- Change device back to Fast ring
- Check for updates
This is the same error that was affecting a previous build, and Microsoft offered the same workaround in that case as well. After going through the steps above, you should be off to the races. If you've been encountering this error, let us know in the comments if you have any success with the above workaround!