diff --git a/changelogs/unreleased/31280-fix-showing-issues-from-pending-delete-projects.yml b/changelogs/unreleased/31280-fix-showing-issues-from-pending-delete-projects.yml
new file mode 100644
index 0000000000000000000000000000000000000000..410480de573270a28e4e55a337474fa2fb96fb1a
--- /dev/null
+++ b/changelogs/unreleased/31280-fix-showing-issues-from-pending-delete-projects.yml
@@ -0,0 +1,4 @@
+---
+title: Fix 500 error due to trying to show issues from pending deleting projects
+merge_request: 10906
+author:
diff --git a/lib/banzai/issuable_extractor.rb b/lib/banzai/issuable_extractor.rb
index c5ce360e1728b2e6a7afa8ea81cd1d6dd855cd71..cbabf9156de465f0de275be680c54e6a6a8759d6 100644
--- a/lib/banzai/issuable_extractor.rb
+++ b/lib/banzai/issuable_extractor.rb
@@ -28,9 +28,13 @@ module Banzai
       issue_parser = Banzai::ReferenceParser::IssueParser.new(project, user)
       merge_request_parser = Banzai::ReferenceParser::MergeRequestParser.new(project, user)
 
-      issue_parser.issues_for_nodes(nodes).merge(
+      issuables_for_nodes = issue_parser.issues_for_nodes(nodes).merge(
         merge_request_parser.merge_requests_for_nodes(nodes)
       )
+
+      # The project for the issue/MR might be pending for deletion!
+      # Filter them out because we don't care about them.
+      issuables_for_nodes.select { |node, issuable| issuable.project }
     end
   end
 end
diff --git a/spec/factories/issues.rb b/spec/factories/issues.rb
index 0b6977e3b17b4ce4bb1ea8745e786a21c0b5bbf9..f1fd1fd7f73c36930a0c3db8de92bdeedf0ac1b2 100644
--- a/spec/factories/issues.rb
+++ b/spec/factories/issues.rb
@@ -8,6 +8,10 @@ FactoryGirl.define do
       confidential true
     end
 
+    trait :opened do
+      state :opened
+    end
+
     trait :closed do
       state :closed
     end
diff --git a/spec/lib/banzai/filter/issuable_state_filter_spec.rb b/spec/lib/banzai/filter/issuable_state_filter_spec.rb
index 600f3c123ed7bd9701e13af85b29f0bc38d27112..9c2399815b9e141dffa0272bbd2554e587269277 100644
--- a/spec/lib/banzai/filter/issuable_state_filter_spec.rb
+++ b/spec/lib/banzai/filter/issuable_state_filter_spec.rb
@@ -6,11 +6,23 @@ describe Banzai::Filter::IssuableStateFilter, lib: true do
 
   let(:user) { create(:user) }
   let(:context) { { current_user: user, issuable_state_filter_enabled: true } }
+  let(:closed_issue) { create_issue(:closed) }
+  let(:project) { create(:empty_project, :public) }
+  let(:other_project) { create(:empty_project, :public) }
 
   def create_link(text, data)
     link_to(text, '', class: 'gfm has-tooltip', data: data)
   end
 
+  def create_issue(state)
+    create(:issue, state, project: project)
+  end
+
+  def create_merge_request(state)
+    create(:merge_request, state,
+      source_project: project, target_project: project)
+  end
+
   it 'ignores non-GFM links' do
     html = %(See <a href="https://google.com/">Google</a>)
     doc = filter(html, current_user: user)
@@ -19,7 +31,6 @@ describe Banzai::Filter::IssuableStateFilter, lib: true do
   end
 
   it 'ignores non-issuable links' do
-    project = create(:empty_project, :public)
     link = create_link('text', project: project, reference_type: 'issue')
     doc = filter(link, context)
 
@@ -27,27 +38,24 @@ describe Banzai::Filter::IssuableStateFilter, lib: true do
   end
 
   it 'ignores issuable links with empty content' do
-    issue = create(:issue, :closed)
-    link = create_link('', issue: issue.id, reference_type: 'issue')
+    link = create_link('', issue: closed_issue.id, reference_type: 'issue')
     doc = filter(link, context)
 
     expect(doc.css('a').last.text).to eq('')
   end
 
   it 'ignores issuable links with custom anchor' do
-    issue = create(:issue, :closed)
-    link = create_link('something', issue: issue.id, reference_type: 'issue')
+    link = create_link('something', issue: closed_issue.id, reference_type: 'issue')
     doc = filter(link, context)
 
     expect(doc.css('a').last.text).to eq('something')
   end
 
   it 'ignores issuable links to specific comments' do
-    issue = create(:issue, :closed)
-    link = create_link("#{issue.to_reference} (comment 1)", issue: issue.id, reference_type: 'issue')
+    link = create_link("#{closed_issue.to_reference} (comment 1)", issue: closed_issue.id, reference_type: 'issue')
     doc = filter(link, context)
 
-    expect(doc.css('a').last.text).to eq("#{issue.to_reference} (comment 1)")
+    expect(doc.css('a').last.text).to eq("#{closed_issue.to_reference} (comment 1)")
   end
 
   it 'ignores merge request links to diffs tab' do
@@ -63,26 +71,36 @@ describe Banzai::Filter::IssuableStateFilter, lib: true do
   end
 
   it 'handles cross project references' do
-    issue = create(:issue, :closed)
-    project = create(:empty_project)
-    link = create_link(issue.to_reference(project), issue: issue.id, reference_type: 'issue')
-    doc = filter(link, context.merge(project: project))
+    link = create_link(closed_issue.to_reference(other_project), issue: closed_issue.id, reference_type: 'issue')
+    doc = filter(link, context.merge(project: other_project))
 
-    expect(doc.css('a').last.text).to eq("#{issue.to_reference(project)} (closed)")
+    expect(doc.css('a').last.text).to eq("#{closed_issue.to_reference(other_project)} (closed)")
   end
 
   it 'does not append state when filter is not enabled' do
-    issue = create(:issue, :closed)
-    link = create_link('text', issue: issue.id, reference_type: 'issue')
+    link = create_link('text', issue: closed_issue.id, reference_type: 'issue')
     context = { current_user: user }
     doc = filter(link, context)
 
     expect(doc.css('a').last.text).to eq('text')
   end
 
+  context 'when project is in pending delete' do
+    before do
+      project.update!(pending_delete: true)
+    end
+
+    it 'does not append issue state' do
+      link = create_link('text', issue: closed_issue.id, reference_type: 'issue')
+      doc = filter(link, context)
+
+      expect(doc.css('a').last.text).to eq('text')
+    end
+  end
+
   context 'for issue references' do
     it 'ignores open issue references' do
-      issue = create(:issue)
+      issue = create_issue(:opened)
       link = create_link(issue.to_reference, issue: issue.id, reference_type: 'issue')
       doc = filter(link, context)
 
@@ -90,7 +108,7 @@ describe Banzai::Filter::IssuableStateFilter, lib: true do
     end
 
     it 'ignores reopened issue references' do
-      issue = create(:issue, :reopened)
+      issue = create_issue(:reopened)
       link = create_link(issue.to_reference, issue: issue.id, reference_type: 'issue')
       doc = filter(link, context)
 
@@ -98,70 +116,79 @@ describe Banzai::Filter::IssuableStateFilter, lib: true do
     end
 
     it 'appends state to closed issue references' do
-      issue = create(:issue, :closed)
-      link = create_link(issue.to_reference, issue: issue.id, reference_type: 'issue')
+      link = create_link(closed_issue.to_reference, issue: closed_issue.id, reference_type: 'issue')
       doc = filter(link, context)
 
-      expect(doc.css('a').last.text).to eq("#{issue.to_reference} (closed)")
+      expect(doc.css('a').last.text).to eq("#{closed_issue.to_reference} (closed)")
     end
   end
 
   context 'for merge request references' do
     it 'ignores open merge request references' do
-      merge_request = create(:merge_request)
+      merge_request = create_merge_request(:opened)
+
       link = create_link(
         merge_request.to_reference,
         merge_request: merge_request.id,
         reference_type: 'merge_request'
       )
+
       doc = filter(link, context)
 
       expect(doc.css('a').last.text).to eq(merge_request.to_reference)
     end
 
     it 'ignores reopened merge request references' do
-      merge_request = create(:merge_request, :reopened)
+      merge_request = create_merge_request(:reopened)
+
       link = create_link(
         merge_request.to_reference,
         merge_request: merge_request.id,
         reference_type: 'merge_request'
       )
+
       doc = filter(link, context)
 
       expect(doc.css('a').last.text).to eq(merge_request.to_reference)
     end
 
     it 'ignores locked merge request references' do
-      merge_request = create(:merge_request, :locked)
+      merge_request = create_merge_request(:locked)
+
       link = create_link(
         merge_request.to_reference,
         merge_request: merge_request.id,
         reference_type: 'merge_request'
       )
+
       doc = filter(link, context)
 
       expect(doc.css('a').last.text).to eq(merge_request.to_reference)
     end
 
     it 'appends state to closed merge request references' do
-      merge_request = create(:merge_request, :closed)
+      merge_request = create_merge_request(:closed)
+
       link = create_link(
         merge_request.to_reference,
         merge_request: merge_request.id,
         reference_type: 'merge_request'
       )
+
       doc = filter(link, context)
 
       expect(doc.css('a').last.text).to eq("#{merge_request.to_reference} (closed)")
     end
 
     it 'appends state to merged merge request references' do
-      merge_request = create(:merge_request, :merged)
+      merge_request = create_merge_request(:merged)
+
       link = create_link(
         merge_request.to_reference,
         merge_request: merge_request.id,
         reference_type: 'merge_request'
       )
+
       doc = filter(link, context)
 
       expect(doc.css('a').last.text).to eq("#{merge_request.to_reference} (merged)")