undefined method `plain_specs' for # (NoMethodError)

Question

I have made a pull of a project that I have in my work and when I tried to run rails db:migrate, the terminal request to install \"Bundler 2\" so I do it.

Answer 1

It is a bug with bundler version 2.1.0.pre.2

I unistalled bundler gem and install different version of bundler gem

$ gem uninstall bundler
$ gem install bundler -v 2.0.2

It should work.

Answer 2

What is your ruby version? I had same problem.

My ruby version is 2.6.3 and my bundle didn't work in this ruby version. (Bundle is already upgraded to 2.0.2),

So I downgraded my bundle to verion 1.17.3 and it worked.

I with this solution will help you.

Answer 3

gem uninstall rubygems-bundler

works for me I am using bundler 2.1.0

REF: https://github.com/bundler/bundler/issues/7492

When showing

ERROR:  While executing gem ... (Gem::InstallError)
    rubygems-bundler is not installed in GEM_HOME, try:
    gem uninstall -i /Users/xxxx/.rvm/rubies/ruby-2.5.7/lib/ruby/gems/2.5.0 rubygems-bundler

Please run

gem uninstall -i /Users/xxxx/.rvm/rubies/ruby-2.5.7/lib/ruby/gems/2.5.0 rubygems-bundler

Answer 4

Ensure you are using a version of ruby that is supported. I ran into this when trying to use jruby-9.2.9. By switching from jruby to ruby the problem went away.

rvm use ruby-2.5.1