spring-commands-rspec | This gem implements the rspec command for Spring | Functional Testing library

I'm trying to revive an old Rails application I worked on several years ago. I'm using ruby 2.3.3 and rails 3.2.15 on the Heroku-16 stack with ClearDB for my MySQL database with the mysql2 adapter. When deploying to Heroku it succeeds on the deploy but crashes when it tries to start the app.

Full stack trace from the Heroku log (updated after fixing activerecord-import gem version per suggestion in first answer):

For my Elastic Beanstalk instance, I am getting a 504 status code response whenever I visit it. When I tail the logs I see the following log on the puma app server:

I cannot figure this out! Any help would be greatly appreciated.

Summary

After upgrading to Rails 5.2.3, my RSpec test fails but the app works fine in development.

The test failure states the asset, an image, is not in the pipeline. The problem is that the image is in the pipeline and the app displays the image correctly in development.

The app and RSpec tests work in previous versions of Rails (4.2 and 5.0)

Error

I'm trying to push a forked repo to Heroku but Heroku won't accept the push because Ruby 2.3.1 wasn't accepted. I changed the version to 2.3.3 in the Gemfile and running bundle install --without production, but oddly enough it was still considered to be 2.3.1. The same things happened even after trying other Ruby versions, such as 2.4.0.

Reference:

I am trying to migrate from Rails 4.2 to Rails 5.0 (running on ruby 2.3) (see plan here https://stackoverflow.com/a/38443616/7374136)

The plan is to:

1. Update the rails gem and all dependencies.
2. Run tests (covering almost our whole code base) for depreciations and fix them.
3. Run rake rails:update to update Rails
4. Adapt the configuration, application classes, breaking changes, ...

Nevertheless, I am blocked at the first step already, updating the rails gem and dependencies. gem 'rails', '4.2.5' -> gem 'rails', '~> 5.0' running: bundle update rails.

I faced multiple dependencies issues, which I fixed by looking for any dependencies that ultimately require rails to be less than 5, and see if those can be updated. Running:

I am trying to run a rails app that uses react and webpacker. All of the node_modules are installed through yarn.

When I boot up the local server using foreman, I get the error:

When I try to push my master branch to Heroku, I get the following output in console. I've tried running bundle install, but that does not resolve. I have Gemfile.lock checked into version control but am not sure if there are discrepancies between my Gemfile and Gemfile.lock that are causing issues.

Any help is greatly appreciated - thanks!

This is my first major upgrade of Rails (v4 to v5). I've done minor upgrades, like 4.1.1 to 4.2 etc...

I've upgraded to 5.1.1, and I'm getting this dependency error in the console

For some reason any time I use a sass glob pattern (e.g. @import "recommends/**/*"; ) and then go to compile my assets for production (it works in development) it's not working (is throwing a File to import not found or unreadable error`).

Any thoughts as to that for which I had not accounted?

Gemfile: