diff --git a/classes/migration/upgrade/v3_4_0/I12140_MissingDecisionConstantsUpdate.php b/classes/migration/upgrade/v3_4_0/I12140_MissingDecisionConstantsUpdate.php
new file mode 100644
index 00000000000..c2f62544eea
--- /dev/null
+++ b/classes/migration/upgrade/v3_4_0/I12140_MissingDecisionConstantsUpdate.php
@@ -0,0 +1,133 @@
+<?php
+
+/**
+ * @file classes/migration/upgrade/v3_4_0/I12140_MissingDecisionConstantsUpdate.php
+ *
+ * Copyright (c) 2025 Simon Fraser University
+ * Copyright (c) 2025 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
+ *
+ * @class I12140_MissingDecisionConstantsUpdate
+ *
+ * @brief Fixed the missing decisions data in stages
+ *
+ * @see https://github.com/pkp/pkp-lib/issues/12140
+ */
+
+namespace APP\migration\upgrade\v3_4_0;
+
+use APP\core\Application;
+use Carbon\Carbon;
+use Illuminate\Support\Facades\DB;
+use PKP\install\DowngradeNotSupportedException;
+
+class I12140_MissingDecisionConstantsUpdate extends \PKP\migration\upgrade\v3_4_0\I7725_DecisionConstantsUpdate
+{
+    /**
+     * Get the decisions constants mappings
+     */
+    public function getDecisionMappings(): array
+    {
+        return [
+            // \PKP\decision\Decision::SKIP_EXTERNAL_REVIEW
+            [
+                'stage_id' => [WORKFLOW_STAGE_ID_SUBMISSION],
+                'current_value' => 19,
+                'updated_value' => 17,
+            ],
+
+            // \PKP\decision\Decision::RECOMMEND_EXTERNAL_REVIEW
+            // OMP 3.3 only offered this at INTERNAL_REVIEW stage
+            // See https://github.com/pkp/pkp-lib/issues/12357
+            [
+                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
+                'current_value' => 15,
+                'updated_value' => 13,
+            ],
+
+            // \PKP\decision\Decision::BACK_FROM_PRODUCTION
+            [
+                'stage_id' => [WORKFLOW_STAGE_ID_PRODUCTION],
+                'current_value' => 31,
+                'updated_value' => 29,
+            ],
+
+            // \PKP\decision\Decision::BACK_FROM_COPYEDITING
+            [
+                'stage_id' => [WORKFLOW_STAGE_ID_EDITING],
+                'current_value' => 32,
+                'updated_value' => 30,
+            ],
+        ];
+    }
+
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        // If the first installed version is 3.4.0-*
+        // nothing to do and return
+        $firstInstalledVersion = DB::table('versions')
+            ->where('product', Application::get()->getName())
+            ->where('product_type', 'core')
+            ->orderBy('date_installed')
+            ->first();
+
+        if ($firstInstalledVersion->major == 3 && $firstInstalledVersion->minor == 4) {
+            return;
+        }
+
+        // Get the current version from which is the upgrading is happening
+        $currentVersion = DB::table('versions')
+            ->where('product', Application::get()->getName())
+            ->where('product_type', 'core')
+            ->where('current', 1)
+            ->first();
+
+        // If NOT upgrading from 3.4.0-*, then fixed migration \APP\migration\upgrade\v3_4_0\I7725_DecisionConstantsUpdate
+        // have the new fix in place and rest of the code does not need to execute
+        if ($currentVersion->major == 3 && $currentVersion->minor != 4) {
+            return;
+        }
+
+        // Upgrading from a 3.4.0-*
+        // Need to figure out the first installed date of 3.4.0-*
+        // Then need to update the decisions made before the first version of 3.4.0-* installed
+        $firstVersionOf34 = DB::table('versions')
+            ->where('product', Application::get()->getName())
+            ->where('product_type', 'core')
+            ->where('major', 3)
+            ->where('minor', 4)
+            ->orderBy('date_installed')
+            ->first();
+
+        $this->configureUpdatedAtColumn();
+
+        collect($this->getDecisionMappings())
+            ->each(
+                fn ($decisionMapping) => DB::table('edit_decisions')
+                    ->when(
+                        isset($decisionMapping['stage_id']) && !empty($decisionMapping['stage_id']),
+                        fn ($query) => $query->whereIn('stage_id', $decisionMapping['stage_id'])
+                    )
+                    ->where('decision', $decisionMapping['current_value'])
+                    ->whereNull('updated_at')
+                    ->where('date_decided', '<', $firstVersionOf34->date_installed)
+                    ->update([
+                        'decision' => $decisionMapping['updated_value'],
+                        'updated_at' => Carbon::now(),
+                    ])
+            );
+
+        $this->removeUpdatedAtColumn();
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        throw new DowngradeNotSupportedException();
+    }
+}
diff --git a/classes/migration/upgrade/v3_4_0/I7725_DecisionConstantsUpdate.php b/classes/migration/upgrade/v3_4_0/I7725_DecisionConstantsUpdate.php
index 800333298b3..84e4c2494db 100644
--- a/classes/migration/upgrade/v3_4_0/I7725_DecisionConstantsUpdate.php
+++ b/classes/migration/upgrade/v3_4_0/I7725_DecisionConstantsUpdate.php
@@ -24,181 +24,38 @@ class I7725_DecisionConstantsUpdate extends \PKP\migration\upgrade\v3_4_0\I7725_
      */
     public function getDecisionMappings(): array
     {
+        // stage_id filtering removed: all old OMP 3.3 decision values (after I7265
+        // stage-splitting) are unique, and the parent class's updated_at tracking
+        // mechanism prevents collisions between sequential mappings (e.g., 15→13
+        // then 13→11). OMP 3.3 had no validation on which decisions could be
+        // recorded at which stages, so decisions can exist at any stage in legacy data.
+        // See https://github.com/pkp/pkp-lib/issues/12357
         return [
-            // \PKP\decision\Decision::INITIAL_DECLINE
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_SUBMISSION],
-                'current_value' => 9,
-                'updated_value' => 8,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_ACCEPT
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 11,
-                'updated_value' => 9,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_PENDING_REVISIONS
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 12,
-                'updated_value' => 10,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_RESUBMIT
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 13,
-                'updated_value' => 11,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_DECLINE
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 14,
-                'updated_value' => 12,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_EXTERNAL_REVIEW
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 15,
-                'updated_value' => 13,
-            ],
-
-            // \PKP\decision\Decision::NEW_EXTERNAL_ROUND
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 16,
-                'updated_value' => 14,
-            ],
-
-            // \PKP\decision\Decision::REVERT_DECLINE
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 17,
-                'updated_value' => 15,
-            ],
-
-            // \PKP\decision\Decision::REVERT_INITIAL_DECLINE
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_SUBMISSION],
-                'current_value' => 18,
-                'updated_value' => 16,
-            ],
-
-            // \PKP\decision\Decision::SKIP_EXTERNAL_REVIEW
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EDITING],
-                'current_value' => 19,
-                'updated_value' => 17,
-            ],
-
-            // \PKP\decision\Decision::SKIP_INTERNAL_REVIEW
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 20,
-                'updated_value' => 18,
-            ],
-
-            // \PKP\decision\Decision::ACCEPT_INTERNAL
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EDITING],
-                'current_value' => 21,
-                'updated_value' => 19,
-            ],
-
-            // \PKP\decision\Decision::PENDING_REVISIONS_INTERNAL
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 22,
-                'updated_value' => 20
-            ],
-
-            // \PKP\decision\Decision::RESUBMIT_INTERNAL
-            [
-                'stage_id' => [],
-                'current_value' => 23,
-                'updated_value' => 21,
-            ],
-
-            // \PKP\decision\Decision::DECLINE_INTERNAL
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 24,
-                'updated_value' => 22,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_ACCEPT_INTERNAL
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 25,
-                'updated_value' => 23,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_PENDING_REVISIONS_INTERNAL
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 26,
-                'updated_value' => 24,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_RESUBMIT_INTERNAL
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 27,
-                'updated_value' => 25,
-            ],
-
-            // \PKP\decision\Decision::RECOMMEND_DECLINE_INTERNAL
-            [
-                'stage_id' => [],
-                'current_value' => 28,
-                'updated_value' => 26,
-            ],
-
-            // \PKP\decision\Decision::REVERT_INTERNAL_DECLINE
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 29,
-                'updated_value' => 27,
-            ],
-
-            // \PKP\decision\Decision::NEW_INTERNAL_ROUND
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 30,
-                'updated_value' => 28,
-            ],
-
-            // \PKP\decision\Decision::BACK_FROM_PRODUCTION
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_EDITING],
-                'current_value' => 31,
-                'updated_value' => 29,
-            ],
-
-            // \PKP\decision\Decision::BACK_FROM_COPYEDITING
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_SUBMISSION, WORKFLOW_STAGE_ID_INTERNAL_REVIEW, WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 32,
-                'updated_value' => 30,
-            ],
-
-            // \PKP\decision\Decision::CANCEL_REVIEW_ROUND
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_SUBMISSION, WORKFLOW_STAGE_ID_INTERNAL_REVIEW, WORKFLOW_STAGE_ID_EXTERNAL_REVIEW],
-                'current_value' => 33,
-                'updated_value' => 31,
-            ],
-
-            // \PKP\decision\Decision::CANCEL_INTERNAL_REVIEW_ROUND
-            [
-                'stage_id' => [WORKFLOW_STAGE_ID_SUBMISSION, WORKFLOW_STAGE_ID_INTERNAL_REVIEW],
-                'current_value' => 34,
-                'updated_value' => 32,
-            ],
+            ['current_value' => 9,  'updated_value' => 8],   // INITIAL_DECLINE
+            ['current_value' => 11, 'updated_value' => 9],   // RECOMMEND_ACCEPT
+            ['current_value' => 12, 'updated_value' => 10],  // RECOMMEND_PENDING_REVISIONS
+            ['current_value' => 13, 'updated_value' => 11],  // RECOMMEND_RESUBMIT
+            ['current_value' => 14, 'updated_value' => 12],  // RECOMMEND_DECLINE
+            ['current_value' => 15, 'updated_value' => 13],  // RECOMMEND_EXTERNAL_REVIEW
+            ['current_value' => 16, 'updated_value' => 14],  // NEW_EXTERNAL_ROUND
+            ['current_value' => 17, 'updated_value' => 15],  // REVERT_DECLINE
+            ['current_value' => 18, 'updated_value' => 16],  // REVERT_INITIAL_DECLINE
+            ['current_value' => 19, 'updated_value' => 17],  // SKIP_EXTERNAL_REVIEW
+            ['current_value' => 20, 'updated_value' => 18],  // SKIP_INTERNAL_REVIEW
+            ['current_value' => 21, 'updated_value' => 19],  // ACCEPT_INTERNAL
+            ['current_value' => 22, 'updated_value' => 20],  // PENDING_REVISIONS_INTERNAL
+            ['current_value' => 23, 'updated_value' => 21],  // RESUBMIT_INTERNAL
+            ['current_value' => 24, 'updated_value' => 22],  // DECLINE_INTERNAL
+            ['current_value' => 25, 'updated_value' => 23],  // RECOMMEND_ACCEPT_INTERNAL
+            ['current_value' => 26, 'updated_value' => 24],  // RECOMMEND_PENDING_REVISIONS_INTERNAL
+            ['current_value' => 27, 'updated_value' => 25],  // RECOMMEND_RESUBMIT_INTERNAL
+            ['current_value' => 28, 'updated_value' => 26],  // RECOMMEND_DECLINE_INTERNAL
+            ['current_value' => 29, 'updated_value' => 27],  // REVERT_INTERNAL_DECLINE
+            ['current_value' => 30, 'updated_value' => 28],  // NEW_INTERNAL_ROUND
+            ['current_value' => 31, 'updated_value' => 29],  // BACK_FROM_PRODUCTION
+            ['current_value' => 32, 'updated_value' => 30],  // BACK_FROM_COPYEDITING
+            ['current_value' => 33, 'updated_value' => 31],  // CANCEL_REVIEW_ROUND
+            ['current_value' => 34, 'updated_value' => 32],  // CANCEL_INTERNAL_REVIEW_ROUND
         ];
     }
 }
diff --git a/dbscripts/xml/upgrade.xml b/dbscripts/xml/upgrade.xml
index 5ce7ce8c93e..27d352721df 100644
--- a/dbscripts/xml/upgrade.xml
+++ b/dbscripts/xml/upgrade.xml
@@ -211,6 +211,11 @@
 		<migration class="APP\migration\upgrade\v3_4_0\I9822_ChangeUsageStatsTemporaryTablesIndexes"/>
 	</upgrade>
 
+	<upgrade minversion="3.4.0.0" maxversion="3.4.0.10">
+		<!-- Only existing 3.4 installations upgraded from pre-3.4 that need it, not any new 3.4 installations -->
+		<migration class="APP\migration\upgrade\v3_4_0\I12140_MissingDecisionConstantsUpdate"/>
+	</upgrade>
+
 	<!-- Update plugin configuration - should be done as the final upgrade task -->
 	<code function="addPluginVersions" />
 </install>