diff --git a/Dockerfile b/Dockerfile
index 67cc00a209..3bf34fb737 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -44,7 +44,7 @@ ENV USER_REPORT_KEY $USER_REPORT_KEY
 RUN curl -sL https://deb.nodesource.com/setup_12.x | bash -
 RUN apt-get update \
     && apt-get install -y --no-install-recommends \
-        postgresql-client nodejs build-essential patch zlib1g-dev liblzma-dev libicu-dev
+       postgresql-client nodejs build-essential patch zlib1g-dev liblzma-dev libicu-dev shared-mime-info
 RUN npm install -g yarn
 
 # Create app directory
diff --git a/Gemfile b/Gemfile
index 24cfa84b33..0d241805ec 100644
--- a/Gemfile
+++ b/Gemfile
@@ -69,6 +69,10 @@ gem 'sidekiq', '>= 6.1.0'
 gem 'listen', '>= 3.0.5', '< 3.2'
 gem 'appsignal'
 
+# 0.3.5 won't work anymore
+# https://github.com/rails/rails/issues/41750
+gem "mimemagic", '0.3.8'
+
 group :development, :test do
   gem 'dotenv-rails'
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
diff --git a/Gemfile.lock b/Gemfile.lock
index d4d0c3a0ba..2a77ce8369 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -216,14 +216,15 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (1.0.0)
-    mimemagic (0.3.5)
+    mimemagic (0.3.8)
+      nokogiri (~> 1)
     mini_mime (1.0.2)
     mini_portile2 (2.5.0)
     minitest (5.14.4)
     msgpack (1.2.4)
     multipart-post (2.0.0)
     nio4r (2.5.7)
-    nokogiri (1.11.1)
+    nokogiri (1.11.2)
       mini_portile2 (~> 2.5.0)
       racc (~> 1.4)
     oj (3.6.8)
@@ -431,6 +432,7 @@ DEPENDENCIES
   json-schema
   kaminari
   listen (>= 3.0.5, < 3.2)
+  mimemagic (= 0.3.8)
   oj
   pg (~> 0.20)
   pg_search
diff --git a/README.md b/README.md
index 7f172d1a18..61c80fe875 100644
--- a/README.md
+++ b/README.md
@@ -52,6 +52,19 @@ yarn run rails:install
 
 These will satisfy both the frontend and backend's dependency requirements.
 
+You will probably need to install shared-mime-info in your system:
+https://github.com/rails/rails/issues/41757
+
+(mac)
+```
+brew install shared-mime-info
+```
+
+(linux)
+```
+sudo apt-get install shared-mime-info
+```
+
 #### Setting up the Rails environment
 
 Copy the sample `.env.sample` file to `.env` and modify it as needed to fit the