我尝试将图片上传到帖子时收到此错误。图像指向posts_controller.rb中的错误，特别是行
@post = current_user.posts.build(post_params)
我运行了以下命令但没有成功
heroku restart
rake db:migrate
heroku run rake db:migrate
这是错误日志...
Started POST "/topics/16/posts" for 127.0.0.1 at 2014-09-13 15:54:00 -0400
Processing by PostsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"NSz0oNqCRm9R3w820fLmaqUhnUYpfo+xB2/cp2FxrFE=", "post"=>{"title"=>"jlajsdlajs", "body"=>"jaljdslajdlasjdlkajsldkajslkj", "image"=>#<ActionDispatch::Http::UploadedFile:0x007fb568702a18 @tempfile=#<Tempfile:/var/folders/3k/1093ljv50p9617s4vn704r9w0000gn/T/RackMultipart20140913-844-1cs5s69>, @original_filename="art-painting-gerome-bethseba_wallcoo.com.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"post[image]\"; filename=\"art-painting-gerome-bethseba_wallcoo.com.jpg\"\r\nContent-Type: image/jpeg\r\n">}, "commit"=>"Create Post", "topic_id"=>"16"}
Topic Load (0.2ms) SELECT "topics".* FROM "topics" WHERE "topics"."id" = ? LIMIT 1 [["id", "16"]]
User Load (0.4ms) SELECT "users".* FROM "users" WHERE "users"."id" = 6 ORDER BY "users"."id" ASC LIMIT 1
Completed 500 Internal Server Error in 8ms
NoMethodError - undefined method `image_will_change!' for #<Post:0x007fb56b839078>:
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