因此，我通常没有任何问题将应用程序部署到heroku，但是，在这种特定情况下，我得到了预编译失败的错误...
这条线在我看来很突出：
remote: NoMethodError: undefined method `[]' for nil:NilClass
但这里是完整的错误日志：
remote: Bundle completed (9.35s)
remote: Cleaning up the bundler cache.
remote: Removing carrierwave (0.10.0)
remote: Removing foreigner (1.7.4)
remote: Removing mailboxer (0.12.5)
remote: -----> Preparing app for Rails asset pipeline
remote: Running: rake assets:precompile
remote: rake aborted!
remote: NoMethodError: undefined method `[]' for nil:NilClass
remote: (in /tmp/build_3dacd5df86a31726215c3dc3c1c22600/app/assets/stylesheets/application.css)
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/sass_functions.rb:63:in `sprockets_context'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-rails-4.0.5/lib/sass/rails/helpers.rb:23:in `asset_url'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/script/funcall.rb:113:in `_perform'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/script/node.rb:40:in `perform'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:298:in `visit_prop'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:100:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `map'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `block in visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:356:in `visit_directive'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:100:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `map'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `block in visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:128:in `visit_root'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:100:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:7:in `visit'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/root_node.rb:20:in `render'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/engine.rb:315:in `_render'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/engine.rb:262:in `render'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/sass_compressor.rb:24:in `evaluate'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/tilt-1.4.1/lib/tilt/template.rb:103:in `render'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/context.rb:197:in `block in evaluate'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/context.rb:194:in `each'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/context.rb:194:in `evaluate'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/bundled_asset.rb:25:in `initialize'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/base.rb:377:in `new'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/base.rb:377:in `build_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/index.rb:94:in `block in build_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/caching.rb:58:in `cache_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/index.rb:93:in `build_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/base.rb:287:in `find_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/index.rb:61:in `find_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:211:in `block in find_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:257:in `benchmark'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:210:in `find_asset'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:119:in `block in compile'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:118:in `each'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:118:in `compile'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.3.1/lib/sprockets/rails/task.rb:70:in `block (3 levels) in define'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/rake/sprocketstask.rb:146:in `with_logger'
remote: /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.3.1/lib/sprockets/rails/task.rb:69:in `block (2 levels) in define'
remote: Tasks: TOP => assets:precompile
remote: (See full trace by running task with --trace)
remote: !
remote: ! Precompiling assets failed.
remote: !
remote:
remote: ! Push rejected, failed to compile Ruby app
remote:
remote: Verifying deploy...
remote:
remote: ! Push rejected to fakename-dev.
remote:
To git@heroku.com:fakename-dev.git
! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'git@heroku.com:fakename-dev.git'
我做错了什么，我该如何解决这个问题？
干杯！
答案 0 :(得分：4)
这是交易，我们有application.css以某种方式忽略了预编译中其他.scss文件中的错误，因此我们在本地预编译了资产但无法在heroku上预编译它们。
我决定将application.css重命名为application.css.scss，现在当我运行assets:precompile任务时，我得到的错误与heroku相同，这让我可以调查问题所在。< / p>
这是一个缩小的bootstrap.css文件（来自设计师），我们团队中的开发人员决定通过缩进并改变字体路径来重新考虑因素而不将扩展名更改为.scss以获得image-url和asset-url帮助者可用..无论如何，我放弃了所有这些并使用了修复图标问题的bootstrap gem。
总结，将.scss添加到样式表中，以便在预编译时更快地找到问题。
答案 1 :(得分：0)
运行命令：RAILS_ENV=production bundle exec rake assets:precompile，您可以轻松地解决错误。
答案 2 :(得分：0)
显然，这可能是由于多种原因造成的，但就我而言，将这行public_root_path: public
添加到 webpacker.yml 已解决了该问题
default: &default
public_root_path: public
...