Bundler could not find compatible versions for gem "spree_backend":
In snapshot (Gemfile.lock):
spree_backend (= 4.0.0)
In Gemfile:
spree (~> 4.0) was resolved to 4.0.0, which depends on
spree_backend (= 4.0.0)
spree_multi_currency was resolved to 3.3.0.rc1, which depends on
spree_backend (>= 3.1.0, < 4.0)
spree_multi_vendor was resolved to 1.4.0, which depends on
spree_backend (>= 3.2.0, < 5.0)
Running `bundle update` will rebuild your snapshot from scratch, using only
the gems in your Gemfile, which may resolve the conflict.