diff --git a/app/assets/stylesheets/new_design/card.scss b/app/assets/stylesheets/new_design/card.scss
index 9d2300b16..5506635af 100644
--- a/app/assets/stylesheets/new_design/card.scss
+++ b/app/assets/stylesheets/new_design/card.scss
@@ -46,6 +46,18 @@
     }
   }
 
+  ul {
+    list-style-type: disc;
+    list-style-position: inside;
+    padding-left: $default-padding;
+  }
+
+  ol {
+    list-style-type: decimal;
+    list-style-position: inside;
+    padding-left: $default-padding;
+  }
+
   p:not(:last-of-type) {
     margin-bottom: $default-spacer;
   }
diff --git a/app/helpers/dossier_helper.rb b/app/helpers/dossier_helper.rb
index f4dabce51..bd1e6d95f 100644
--- a/app/helpers/dossier_helper.rb
+++ b/app/helpers/dossier_helper.rb
@@ -69,4 +69,27 @@ module DossierHelper
       dossier.state
     end
   end
+
+  # On the 22/01/2020, a technical error on the demarches-simplifees.fr
+  # instance caused some files attached to some dossiers to be deleted.
+  #
+  # This method returns true if the dossier contained attachments
+  # whose files were deleted during this incident.
+  def has_lost_attachments(dossier)
+    if dinum_instance?
+      dossiers_with_lost_attachments_ids.include?(dossier.id)
+    else
+      false
+    end
+  end
+
+  private
+
+  def dinum_instance?
+    ENV['APP_HOST']&.ends_with?('demarches-simplifiees.fr')
+  end
+
+  def dossiers_with_lost_attachments_ids
+    @@ids ||= YAML.load_file(Rails.root.join('config', 'dossiers-with-lost-attachments.yml'))
+  end
 end
diff --git a/app/views/shared/dossiers/_demande.html.haml b/app/views/shared/dossiers/_demande.html.haml
index 55870541c..d8a96eaae 100644
--- a/app/views/shared/dossiers/_demande.html.haml
+++ b/app/views/shared/dossiers/_demande.html.haml
@@ -24,5 +24,7 @@
   .tab-title Formulaire
   - champs = dossier.champs.includes(:type_de_champ)
   - if champs.any? || dossier.procedure.routee?
+    - if has_lost_attachments(dossier)
+      = render partial: "shared/dossiers/lost_attachments", locals: { dossier: dossier }
     .card
       = render partial: "shared/dossiers/champs", locals: { champs: champs, dossier: dossier, demande_seen_at: demande_seen_at, profile: profile }
diff --git a/app/views/shared/dossiers/_lost_attachments.html.haml b/app/views/shared/dossiers/_lost_attachments.html.haml
new file mode 100644
index 000000000..1195d8edc
--- /dev/null
+++ b/app/views/shared/dossiers/_lost_attachments.html.haml
@@ -0,0 +1,27 @@
+/# FIXME: add a specific wording for Usagers
+.card.warning
+  .card-title Des pièces jointes de ce dossier peuvent être manquantes.
+  %p
+    Suite à un incident survenu le 21 janvier, demarche-simplifiees.fr a perdu par erreur une partie des pièces jointes de ce dossier.
+
+  - if dossier.en_construction?
+    %p
+      Si une ou plusieurs pièces jointes manquent, nous vous invitons à
+      = succeed ',' do
+        = link_to 'contacter le demandeur', messagerie_instructeur_dossier_path(dossier.procedure, dossier)
+      pour lui demander de
+      = succeed '.' do
+        %strong renvoyer les pièces jointes nécessaires
+
+  - else
+    %p
+      Si une ou plusieurs pièces jointes essentielles manquent, nous vous invitons à :
+      %ol
+        %li repasser ce dossier en construction ;
+        %li<
+          = link_to 'contacter le demandeur ', messagerie_instructeur_dossier_path(dossier.procedure, dossier)
+          pour lui demander de
+          = succeed '.' do
+            %strong renvoyer les pièces jointes nécessaires
+
+  %p Le demandeur de ce dossier a également été prévenu. Nous nous excusons pour la gêne occasionnée.
diff --git a/config/dossiers-with-lost-attachments.yml b/config/dossiers-with-lost-attachments.yml
new file mode 100644
index 000000000..7b0243429
--- /dev/null
+++ b/config/dossiers-with-lost-attachments.yml
@@ -0,0 +1,946 @@
+# On the 22/01/2020, a technical error on the demarches-simplifees.fr
+# instance made us delete some files attached to some dossiers.
+#
+# This list contains the ids of all dossiers where some attached
+# file was mistakenly deleted during this incident.
+- 22
+- 9224
+- 9244
+- 9489
+- 9495
+- 11045
+- 14311
+- 14530
+- 14553
+- 14569
+- 14616
+- 14619
+- 15325
+- 15331
+- 16448
+- 17848
+- 18190
+- 18308
+- 18855
+- 18929
+- 18946
+- 18965
+- 19284
+- 19697
+- 19698
+- 19872
+- 20334
+- 20663
+- 20931
+- 21015
+- 21024
+- 21620
+- 21753
+- 21782
+- 21865
+- 21871
+- 21876
+- 21938
+- 21963
+- 21971
+- 22011
+- 22042
+- 22045
+- 22063
+- 22068
+- 22108
+- 22279
+- 22434
+- 22488
+- 22523
+- 24277
+- 25275
+- 26223
+- 26228
+- 27069
+- 27213
+- 29366
+- 29386
+- 29486
+- 31179
+- 31983
+- 32004
+- 32323
+- 32325
+- 32492
+- 32497
+- 35072
+- 35074
+- 35193
+- 35232
+- 35308
+- 35323
+- 35357
+- 35442
+- 35486
+- 35496
+- 35554
+- 35644
+- 36659
+- 38984
+- 39026
+- 39099
+- 39158
+- 39287
+- 39314
+- 39352
+- 39359
+- 39371
+- 39380
+- 39390
+- 39403
+- 39493
+- 39526
+- 41106
+- 41111
+- 43566
+- 43570
+- 43571
+- 43572
+- 43578
+- 43741
+- 43785
+- 43791
+- 43884
+- 43928
+- 43935
+- 43937
+- 44013
+- 44035
+- 45123
+- 48500
+- 48690
+- 52921
+- 53029
+- 53067
+- 53097
+- 53118
+- 53147
+- 53152
+- 53153
+- 53154
+- 53155
+- 53159
+- 53171
+- 53176
+- 53178
+- 53207
+- 53208
+- 53218
+- 53472
+- 53981
+- 54002
+- 56253
+- 57216
+- 57689
+- 58003
+- 58411
+- 58721
+- 59445
+- 59925
+- 61917
+- 62547
+- 62551
+- 62552
+- 62956
+- 63035
+- 63607
+- 63615
+- 65154
+- 66268
+- 66379
+- 66963
+- 67066
+- 68688
+- 68705
+- 68710
+- 68737
+- 68929
+- 68943
+- 69023
+- 69026
+- 69510
+- 69521
+- 69546
+- 70148
+- 70224
+- 72653
+- 76114
+- 79303
+- 79863
+- 79929
+- 79951
+- 79976
+- 80032
+- 84640
+- 93404
+- 98647
+- 99294
+- 101868
+- 103748
+- 104097
+- 107096
+- 109146
+- 113137,
+- 113690
+- 113707
+- 113711
+- 113722
+- 113743
+- 117270
+- 118003
+- 119395
+- 120824
+- 121498
+- 124009
+- 125430
+- 127024
+- 130735
+- 132389
+- 132942
+- 133317
+- 133697
+- 137347
+- 137374
+- 137427
+- 137525
+- 137900
+- 138272
+- 138436
+- 138466
+- 138515
+- 138550
+- 138631
+- 138703
+- 138990
+- 139296
+- 139371
+- 140604
+- 140811
+- 141142
+- 141227
+- 148609
+- 153917
+- 156644
+- 157401
+- 184400
+- 190035
+- 191350
+- 193213
+- 193783
+- 194088
+- 198497
+- 200002
+- 200005
+- 200017
+- 200041
+- 200048
+- 200060
+- 200061
+- 200062
+- 200081
+- 200086
+- 200089
+- 200094
+- 200098
+- 200100
+- 200108
+- 200109
+- 200113
+- 200128
+- 200138
+- 200140
+- 200143
+- 200154
+- 200158
+- 200161
+- 200163
+- 200169
+- 200182
+- 200186
+- 200195
+- 200202
+- 200208
+- 200211
+- 200263
+- 200267
+- 200448
+- 200685
+- 200757
+- 200784
+- 200787
+- 201021
+- 201315
+- 201576
+- 201921
+- 201986
+- 202015
+- 203553
+- 203630
+- 204737
+- 204866
+- 204924
+- 204982
+- 205021
+- 205265
+- 205424
+- 205655
+- 205659
+- 205847
+- 205940
+- 205954
+- 205987
+- 206013
+- 206089
+- 206108
+- 206170
+- 206179
+- 206217
+- 206237
+- 206285
+- 206288
+- 206290
+- 206300
+- 206374
+- 206472
+- 206490
+- 206494
+- 206515
+- 206532
+- 206589
+- 206612
+- 206734
+- 206741
+- 206782
+- 206807
+- 206828
+- 206835
+- 206856
+- 206887
+- 206904
+- 206909
+- 206913
+- 206931
+- 206964
+- 206972
+- 206977
+- 206979
+- 206992
+- 207004
+- 207006
+- 207032
+- 207061
+- 207078
+- 207103
+- 207104
+- 207118
+- 207181
+- 207183
+- 207197
+- 207207
+- 207236
+- 207537
+- 207734
+- 207773
+- 208009
+- 208153
+- 208186
+- 208199
+- 208379
+- 208422
+- 208545
+- 208549
+- 208873
+- 208903
+- 209151
+- 209392
+- 209397
+- 209873
+- 210103
+- 210175
+- 210959
+- 211018
+- 211144
+- 211197
+- 211852
+- 212322
+- 212359
+- 212493
+- 212503
+- 212955
+- 212986
+- 213596
+- 213598
+- 213612
+- 213625
+- 213694
+- 213712
+- 213749
+- 214123
+- 214592
+- 215503
+- 215510
+- 215742
+- 215756
+- 216263
+- 216360
+- 216620
+- 217131
+- 217159
+- 217215
+- 217320
+- 217361
+- 217373
+- 217487
+- 217507
+- 217518
+- 217587
+- 217677
+- 217714
+- 217790
+- 217796
+- 217850
+- 217859
+- 217871
+- 217875
+- 218370
+- 218419
+- 219341
+- 220675
+- 221967
+- 222266
+- 222801
+- 222868
+- 222875
+- 222946
+- 222949
+- 222965
+- 223154
+- 223303
+- 223329
+- 223368
+- 224064
+- 224290
+- 225117
+- 227153
+- 227161
+- 227816
+- 227931
+- 228074
+- 228666
+- 228703
+- 228776
+- 228918
+- 228926
+- 229050
+- 229086
+- 229109
+- 229114
+- 229553
+- 230338
+- 230353
+- 230479
+- 230539
+- 230574
+- 230582
+- 231261
+- 232521
+- 232740
+- 232916
+- 232934
+- 232958
+- 233008
+- 233047
+- 233160
+- 233197
+- 233211
+- 233556
+- 233605
+- 233712
+- 235322
+- 236625
+- 237371
+- 237439
+- 237605
+- 238276
+- 239412
+- 239500
+- 239603
+- 239777
+- 239805
+- 239829
+- 239850
+- 239858
+- 241496
+- 241557
+- 241598
+- 241788
+- 241824
+- 241858
+- 241879
+- 241910
+- 241927
+- 241934
+- 241936
+- 241939
+- 241950
+- 241952
+- 241955
+- 241956
+- 241959
+- 241969
+- 241970
+- 241985
+- 241987
+- 241991
+- 241996
+- 242414
+- 242725
+- 242800
+- 242808
+- 242814
+- 242820
+- 242840
+- 242845
+- 242937
+- 242942
+- 242972
+- 242973
+- 242975
+- 242997
+- 243133
+- 243234
+- 243237
+- 243240
+- 243273
+- 243290
+- 243335
+- 243339
+- 243429
+- 245309
+- 245460
+- 247557
+- 248202
+- 248537
+- 248567
+- 248592
+- 248726
+- 248776
+- 249018
+- 249342
+- 249352
+- 249563
+- 250149
+- 250471
+- 250489
+- 250502
+- 250504
+- 250509
+- 250511
+- 250530
+- 251386
+- 252994
+- 254055
+- 254211
+- 254972
+- 255013
+- 255078
+- 255082
+- 255329
+- 255925
+- 255990
+- 256083
+- 256084
+- 256296
+- 256472
+- 257228
+- 258640
+- 258982
+- 259131
+- 259147
+- 259204
+- 261038
+- 261117
+- 261118
+- 261170
+- 261452
+- 263654
+- 264489
+- 265036
+- 265333
+- 265983
+- 266034
+- 266057
+- 266062
+- 266069
+- 266071
+- 266205
+- 267145
+- 267322
+- 267404
+- 267708
+- 268223
+- 268652
+- 268654
+- 268678
+- 268728
+- 268731
+- 268764
+- 268885
+- 269421
+- 269444
+- 269518
+- 269560
+- 269574
+- 269575
+- 270213
+- 272346
+- 272891
+- 273169
+- 274183
+- 274478
+- 274634
+- 274730
+- 275900
+- 279329
+- 279348
+- 280975
+- 281779
+- 281804
+- 282877
+- 283362
+- 283378
+- 283392
+- 283395
+- 283495
+- 283845
+- 284616
+- 284622
+- 284675
+- 284687
+- 284774
+- 284838
+- 284880
+- 285060
+- 285230
+- 285575
+- 285603
+- 287488
+- 288210
+- 289529
+- 289530
+- 289811
+- 289844
+- 289859
+- 290754
+- 291018
+- 291621
+- 293625
+- 293634
+- 296214
+- 298172
+- 298355
+- 298942
+- 299000
+- 306186
+- 310318
+- 310544
+- 310730
+- 311019
+- 311728
+- 312509
+- 312531
+- 313699
+- 330729
+- 337282
+- 344150
+- 351128
+- 360286
+- 374944
+- 386682
+- 386850
+- 409245
+- 410749
+- 429085
+- 453060
+- 473146
+- 473183
+- 477625
+- 482733
+- 485936
+- 486996
+- 501423
+- 524299
+- 525738
+- 525916
+- 525932
+- 525936
+- 529745
+- 529870
+- 542902
+- 546362
+- 546394
+- 546406
+- 546416
+- 546519
+- 551264
+- 551276
+- 552058
+- 555081
+- 571316
+- 574190
+- 574209
+- 591896
+- 600483
+- 600501
+- 600863
+- 601157
+- 619683
+- 620774
+- 627219
+- 628388
+- 628633
+- 628675
+- 628701
+- 628743
+- 628746
+- 628763
+- 631292
+- 635784
+- 639656
+- 640229
+- 642227
+- 654699
+- 656113
+- 665439
+- 666028
+- 666790
+- 670294
+- 671241
+- 671245
+- 671259
+- 671268
+- 671458
+- 677528
+- 679414
+- 690281
+- 690749
+- 692168
+- 695653
+- 695727
+- 695768
+- 695791
+- 696013
+- 696428
+- 715997
+- 719236
+- 726969
+- 726981
+- 727014
+- 727551
+- 756386
+- 756402
+- 762500
+- 766726
+- 767963
+- 771492
+- 773982
+- 775235
+- 777837
+- 780557
+- 781158
+- 781502
+- 781503
+- 784077
+- 784298
+- 784403
+- 792304
+- 794024
+- 794606
+- 795345
+- 796814
+- 798434
+- 798893
+- 799196
+- 799200
+- 800093
+- 802666
+- 802679
+- 802707
+- 802709
+- 802716
+- 808711
+- 808740
+- 808742
+- 808766
+- 808767
+- 808784
+- 808797
+- 808876
+- 808926
+- 808935
+- 808937
+- 808939
+- 808940
+- 808943
+- 808947
+- 808958
+- 808963
+- 808967
+- 808982
+- 808983
+- 808994
+- 809002
+- 809004
+- 809007
+- 811190
+- 818427
+- 818724
+- 819171
+- 819725
+- 828064
+- 828292
+- 828535
+- 828577
+- 828607
+- 828641
+- 828705
+- 828741
+- 828778
+- 828782
+- 828788
+- 828819
+- 829128
+- 829239
+- 832186
+- 839927
+- 841809
+- 842330
+- 845358
+- 846642
+- 853954
+- 855891
+- 859844
+- 860016
+- 860043
+- 860050
+- 860059
+- 860062
+- 860067
+- 860520
+- 860555
+- 861195
+- 861222
+- 863696
+- 888447
+- 898772
+- 910362
+- 916218
+- 920528
+- 924844
+- 931770
+- 933988
+- 934004
+- 934005
+- 934008
+- 934009
+- 934010
+- 934013
+- 934014
+- 934019
+- 934029
+- 934033
+- 934046
+- 934058
+- 934060
+- 938750
+- 946941
+- 949162
+- 951110
+- 951227
+- 955534
+- 959860
+- 960038
+- 962441
+- 962443
+- 962515
+- 962547
+- 962560
+- 962664
+- 963634
+- 966627
+- 969062
+- 985102
+- 990079
+- 990281
+- 991542
+- 999193
+- 1009535
+- 1016896
+- 1018675
+- 1019395
+- 1020295
+- 1020509
+- 1020960
+- 1020969
+- 1020982
+- 1021109
+- 1023811
+- 1027181
+- 1028190
+- 1035967
+- 1036338
+- 1038182
+- 1047230
+- 1048403
+- 1048429
+- 1048938
+- 1049968
+- 1050075
+- 1063901
+- 1063941
+- 1063942
+- 1079027
+- 1079344
+- 1083246
+- 1086139
+- 1088337
+- 1092801
+- 1102942
+- 1110614
+- 1110620
+- 1112775
+- 1116822
+- 1121711
+- 1140138
+- 1143324
+- 1145406
+- 1153823
+- 1157409
+- 1164993
+- 1165566
+- 1168238
+- 1169529
+- 1174555
+- 1182043
+- 1184647
+- 1187042
+- 1188538
+- 1206673
+- 1206824
+- 1206939
+- 1206954
+- 1206967
+- 1206969
+- 1249330
+- 1249377
+- 1249815
+- 1263647
+- 1279054
+- 1280300
+- 1280341
diff --git a/spec/helpers/dossier_helper_spec.rb b/spec/helpers/dossier_helper_spec.rb
index 2296235f9..aea4f92de 100644
--- a/spec/helpers/dossier_helper_spec.rb
+++ b/spec/helpers/dossier_helper_spec.rb
@@ -183,4 +183,33 @@ RSpec.describe DossierHelper, type: :helper do
       it { is_expected.to eq('without_continuation') }
     end
   end
+
+  describe '.has_lost_attachments' do
+    let(:procedure) { create(:procedure, :published) }
+    let(:dossier_with_lost_attachments)    { create(:dossier, procedure: procedure) }
+    let(:dossier_without_lost_attachments) { create(:dossier, procedure: procedure) }
+
+    before do
+      expect(ENV).to receive(:[]).with('APP_HOST').at_least(:once).and_return(app_host)
+      allow(helper).to receive(:dossiers_with_lost_attachments_ids).and_return([dossier_with_lost_attachments.id])
+    end
+
+    context 'on the DINUM instance' do
+      let(:app_host) { 'demarches-simplifiees.fr' }
+
+      it 'returns true for dossiers that lost attachments' do
+        expect(helper.has_lost_attachments(dossier_with_lost_attachments)).to be(true)
+        expect(helper.has_lost_attachments(dossier_without_lost_attachments)).to be(false)
+      end
+    end
+
+    context 'on another instance' do
+      let(:app_host) { 'polynesie-francaise.pref.gouv.fr' }
+
+      it 'returns false for all dossiers' do
+        expect(helper.has_lost_attachments(dossier_with_lost_attachments)).to be(false)
+        expect(helper.has_lost_attachments(dossier_without_lost_attachments)).to be(false)
+      end
+    end
+  end
 end
diff --git a/spec/views/shared/dossiers/_demande.html.haml_spec.rb b/spec/views/shared/dossiers/_demande.html.haml_spec.rb
index 701e078e4..fbf5d4e4a 100644
--- a/spec/views/shared/dossiers/_demande.html.haml_spec.rb
+++ b/spec/views/shared/dossiers/_demande.html.haml_spec.rb
@@ -9,24 +9,24 @@ describe 'shared/dossiers/demande.html.haml', type: :view do
     sign_in(current_instructeur.user)
   end
 
-  subject! { render 'shared/dossiers/demande.html.haml', dossier: dossier, demande_seen_at: nil, profile: 'usager' }
+  subject { render 'shared/dossiers/demande.html.haml', dossier: dossier, demande_seen_at: nil, profile: 'usager' }
 
   context 'when dossier was created by an etablissement' do
     let(:etablissement) { create(:etablissement) }
 
     it 'renders the etablissement infos' do
-      expect(rendered).to include(etablissement.entreprise_raison_sociale)
-      expect(rendered).to include(etablissement.entreprise_siret_siege_social)
-      expect(rendered).to include(etablissement.entreprise_forme_juridique)
+      expect(subject).to include(etablissement.entreprise_raison_sociale)
+      expect(subject).to include(etablissement.entreprise_siret_siege_social)
+      expect(subject).to include(etablissement.entreprise_forme_juridique)
     end
 
     context 'and entreprise is an association' do
       let(:etablissement) { create(:etablissement, :is_association) }
 
       it 'renders the association infos' do
-        expect(rendered).to include(etablissement.association_rna)
-        expect(rendered).to include(etablissement.association_titre)
-        expect(rendered).to include(etablissement.association_objet)
+        expect(subject).to include(etablissement.association_rna)
+        expect(subject).to include(etablissement.association_titre)
+        expect(subject).to include(etablissement.association_objet)
       end
     end
   end
@@ -35,10 +35,10 @@ describe 'shared/dossiers/demande.html.haml', type: :view do
     let(:individual) { create(:individual) }
 
     it 'renders the individual identity infos' do
-      expect(rendered).to include(individual.gender)
-      expect(rendered).to include(individual.nom)
-      expect(rendered).to include(individual.prenom)
-      expect(rendered).to include(I18n.l(individual.birthdate))
+      expect(subject).to include(individual.gender)
+      expect(subject).to include(individual.nom)
+      expect(subject).to include(individual.prenom)
+      expect(subject).to include(I18n.l(individual.birthdate))
     end
   end
 
@@ -47,7 +47,17 @@ describe 'shared/dossiers/demande.html.haml', type: :view do
 
     it 'renders the champs' do
       dossier.champs.each do |champ|
-        expect(rendered).to include(champ.libelle)
+        expect(subject).to include(champ.libelle)
+      end
+    end
+
+    context 'when the dossier lost some attachments' do
+      before do
+        expect(view).to receive(:has_lost_attachments).and_return(true)
+      end
+
+      it 'displays a warning message' do
+        expect(subject).to include('Des pièces jointes de votre dossier peuvent être manquantes.')
       end
     end
   end