uninitialized constant OmniAuth::Strategies::LinkedIn::MultiJson error when authenticating with LinkedIn about omniauth-linkedin

[jmay]

I experienced this. omniauth-linkedin does not specify multi_json as a dependency. So if you don't declare multi_json explicitly in your Gemfile or have it pulled in via some other gem, this error will occur.

[Mingus85]

I have the same problem in Rails 5. installing multi_json seperately does not help

[colinmccann]

I had the same issue after upgrading to Rails 5.2.2. Only in production, worked fine in dev. Declaring multi_json in the Gemfile before the omniauth and omniauth-linkedin fixed the issue