Through 40+ version releases we always provided a single click update button to upgrade your concrete5 site to the latest version. Sometimes you'd have to step through a few major versions to take an ancient site to a latest, but for most installs the path was just a few clicks.
Thankfully now we have the answer for that: these are our migration tools, built for both 5.6 and earlier and concrete5 5.7. These tools are free, open source and available on GitHub.
So what about Add-ons & Themes?
There are effectively two marketplaces. Add-ons/themes for 5.6 will not work on 5.7, and vice versa. Some add-ons/themes may offer a discount if you purchased a similar 5.6 one. Check the top of the page if you're browsing here at concrete5.org to make sure you're buying stuff for the correct install.
What is the life span for 5.6?
Today the community continues to support 5.6 quite effectively with very limited energy from us. If and when we reach a point in the future where security patches and small improvements aren't being incorporated in a timely fashion by our open source community, we will make an end of life announcement and continue providing security patches for 1 year ourselves. Our goal is to make 5.7 so compelling and the migration tools so powerful, that most active 5.6 sites out there will upgrade. As we work towards that end, please continue knowing 5.6 will be secure for years.
Why did you commit this horrible act?
Giving up our backwards compatibilty with this one version was a hard decision and path to take. WordPress never has done it, Drupal does it frequently. It's not something we take lightly, but after 6 years there were just too many new best practices and handy frameworks that had matured to not move forward. In a perfect world we would certainly have preferred to have our cake and eat it too. Creating the opportunity to approach any problem without backwards compatibility concerns was the only way our team was going to get the UX and technical approach into 5.7 that we wanted. Seeing what we've made with 5.7, we know it was well worth it.
We're certainly not going to even consider doing it again for another 6 years, because - yeah, total PITA for everyone, agreed.