In the web and PHP world, the Drupal 7 to 8+ upgrade process. It's really more of a completely rewrite with close to zero code reuse, but the guides didn't make that very clear and the technical docs were just as bad. For such a big project, it was the worst documentation I've ever seen. I got a few weeks in before realizing, man, it's probably a good time to jump ship from Drupal altogether (we moved to Next.js instead) -- best technical decision I ever made as a dev. Not only was the migration much easier, the end result was much cleaner, and the hosting much cheaper, and the devs much easier to hire for.
And that was like half a decade ago, and the migration process has stayed so bad for so long for so many companies that the Drupal org kept delaying the v7 end of life. It was originally supposed to have died in 2021, then they pushed it back a year, then another year, and now it's been pushed back to 2025, but in the meantime third parties have made compatibility shims to run Drupal 7 on top of / within newer versions or something like that. I don't think it's ever going away at this point. There's an entire cottage industry, with their own conferences, around supporting old Drupals. The chaos of Drupal makes the Javascript ecosystem seem simple in comparison, and makes Wordpress look like the epitome of a well-managed project.
It was my first (and last) time working with Drupal. It's the only software I've ever used that I flat-out hated, and swore to never touch ever again. If someone offered me a million dollars a year to maintain a Drupal install, I'd instead pay them to never talk to me again. That migration scarred me for life.
And that was like half a decade ago, and the migration process has stayed so bad for so long for so many companies that the Drupal org kept delaying the v7 end of life. It was originally supposed to have died in 2021, then they pushed it back a year, then another year, and now it's been pushed back to 2025, but in the meantime third parties have made compatibility shims to run Drupal 7 on top of / within newer versions or something like that. I don't think it's ever going away at this point. There's an entire cottage industry, with their own conferences, around supporting old Drupals. The chaos of Drupal makes the Javascript ecosystem seem simple in comparison, and makes Wordpress look like the epitome of a well-managed project.
It was my first (and last) time working with Drupal. It's the only software I've ever used that I flat-out hated, and swore to never touch ever again. If someone offered me a million dollars a year to maintain a Drupal install, I'd instead pay them to never talk to me again. That migration scarred me for life.