diff --git a/app/models/issue.rb b/app/models/issue.rb
index 9b47ce7bd..3debf90ec 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1018,7 +1018,7 @@ class Issue < ApplicationRecord
 
   # Returns true if this issue is blocked by another issue that is still open
   def blocked?
-    !relations_to.detect {|ir| ir.relation_type == 'blocks' && !ir.issue_from.closed?}.nil?
+    relations_to.any? {|ir| ir.relation_type == 'blocks' && ir.issue_from&.closed? == false}
   end
 
   # Returns true if this issue can be closed and if not, returns false and populates the reason
diff --git a/test/unit/issue_test.rb b/test/unit/issue_test.rb
index 7480fbc55..205ba144a 100644
--- a/test/unit/issue_test.rb
+++ b/test/unit/issue_test.rb
@@ -2222,6 +2222,16 @@ class IssueTest < ActiveSupport::TestCase
     assert !blocking_issue.blocked?
   end
 
+  def test_blocked_should_not_raise_an_exception_when_blocing_issue_is_invalid
+    ir = IssueRelation.find_by(issue_from_id: 10, issue_to_id: 9, relation_type: 'blocks')
+    issue = Issue.find(9)
+    assert issue.blocked?
+
+    ir.update_column :issue_from_id, 0  # invalid issue id
+    issue.reload
+    assert !issue.blocked?
+  end
+
   def test_blocked_issues_dont_allow_closed_statuses
     blocked_issue = Issue.find(9)