I got this error after upgrading Ruby from 2.4.5 to 2.6.4 when I opened the Rails console - rails server still worked.

Running via Spring preloader in process 14679
Loading development environment (Rails 5.2.2.1)
Traceback (most recent call...

For example if you use rvm and get this message:

ERROR:  Loading command: install (LoadError)
    no such file to load -- zlib
ERROR:  While executing gem ... (NameError)
    uninitialized constant Gem::Commands::InstallCommand

...

If you're on Ubuntu:

sudo apt-get install ruby-dev

On other platforms: Look for a package containing ruby header files. On Red Hat that's "ruby-devel" likely.

There is a conflict between current capistrano versions and the 2.5.1 net-ssh gem. Make sure you upgrade to 2.5.2, then it should work again.

Today, I ran into trouble on a fairly fresh installed VM, running Ubuntu. I tried to bundle install and got this stacktrace:

Fetching gem metadata from https://rubygems.org/.Unfortunately, a fatal error has occurred. Please see the Bund...

If you get this error (probably because you want to load some modules):

# modprobe xt_comment
FATAL: Could not load /lib/modules/3.2.0-40-generic/modules.dep: No such file or directory

The reason could be that apt-get autoremove al...

Building application assets with esbuild is the new way to do it, and it's great, especially in combination with Sprockets (or Propshaft on Rails 7).
You might be missing some convenience features, though.

Here we cover one specific issue:
Once y...

Say we want …

• to create a Gallery that has a name and has_many :images, which in turn have a caption
• to offer the user a single form to create a gallery with any number of images
• immediate uploads with a progress bar per image
• a snapp...

In this example we assume that not only the storage gem changes but also the file structure on disc.

A general approach

Part A: Create a commit which includes a script that allows you to copy the existing file to the new file structure.
...