diff --git a/app/controllers/execution_environments_controller.rb b/app/controllers/execution_environments_controller.rb
index 5b966fb1..9d714af6 100644
--- a/app/controllers/execution_environments_controller.rb
+++ b/app/controllers/execution_environments_controller.rb
@@ -31,8 +31,8 @@ class ExecutionEnvironmentsController < ApplicationController
 
   def execute_command
     runner = Runner.for(current_user, @execution_environment)
-    output = runner.execute_command(params[:command])
-    render(json: output)
+    output = runner.execute_command(params[:command], raise_exception: false)
+    render json: output
   end
 
   def working_time_query
diff --git a/app/models/execution_environment.rb b/app/models/execution_environment.rb
index 3bb86331..615f9ceb 100644
--- a/app/models/execution_environment.rb
+++ b/app/models/execution_environment.rb
@@ -79,7 +79,7 @@ class ExecutionEnvironment < ApplicationRecord
 
   def working_docker_image?
     runner = Runner.for(author, self)
-    output = runner.execute_command(VALIDATION_COMMAND, raise_exception: true)
+    output = runner.execute_command(VALIDATION_COMMAND)
     errors.add(:docker_image, "error: #{output[:stderr]}") if output[:stderr].present?
   rescue Runner::Error => e
     errors.add(:docker_image, "error: #{e}")
diff --git a/app/models/runner.rb b/app/models/runner.rb
index 21af9d96..63582b6a 100644
--- a/app/models/runner.rb
+++ b/app/models/runner.rb
@@ -64,7 +64,7 @@ class Runner < ApplicationRecord
     Time.zone.now - starting_time # execution duration
   end
 
-  def execute_command(command, raise_exception: false)
+  def execute_command(command, raise_exception: true)
     output = {}
     stdout = +''
     stderr = +''
diff --git a/spec/models/execution_environment_spec.rb b/spec/models/execution_environment_spec.rb
index 2d7b1e48..5b41f4b8 100644
--- a/spec/models/execution_environment_spec.rb
+++ b/spec/models/execution_environment_spec.rb
@@ -162,7 +162,7 @@ describe ExecutionEnvironment do
     it 'executes the validation command' do
       allow(runner).to receive(:execute_command).and_return({})
       working_docker_image?
-      expect(runner).to have_received(:execute_command).with(ExecutionEnvironment::VALIDATION_COMMAND, raise_exception: true)
+      expect(runner).to have_received(:execute_command).with(ExecutionEnvironment::VALIDATION_COMMAND)
     end
 
     context 'when the command produces an error' do