diff --git a/src/base/updater.ts b/src/base/updater.ts
index 090de36..28d8e8e 100644
--- a/src/base/updater.ts
+++ b/src/base/updater.ts
@@ -106,13 +106,16 @@ export class BaseUpdater extends BaseGetter {
         let index = 0;
 
         for (const match of matches) {
+            // Changing the seeding would reset the matches of round >= 2, leaving the scores behind, with no participants.
+            if (match.status === Status.Archived)
+                throw Error('A match of round 1 is archived, which means round 2 was started.');
+
             const opponent1 = slots[index++];
             const opponent2 = slots[index++];
+            const isParticipantLocked = helpers.isMatchParticipantLocked(match);
 
-            const locked = helpers.isMatchParticipantLocked(match);
-            if (!locked) continue;
-
-            if (match.opponent1?.id !== opponent1?.id || match.opponent2?.id !== opponent2?.id)
+            // The match is participant locked, and the participants would have to change.
+            if (isParticipantLocked && (match.opponent1?.id !== opponent1?.id || match.opponent2?.id !== opponent2?.id))
                 throw Error('A match is locked.');
         }
     }
diff --git a/test/update.spec.js b/test/update.spec.js
index c131681..eba63d4 100644
--- a/test/update.spec.js
+++ b/test/update.spec.js
@@ -897,6 +897,41 @@ describe('Seeding', () => {
         ]), 'A match is locked.');
     });
 
+    it('should throw if a match is archived and would have to be changed', async () => {
+        await manager.update.seeding(0, [
+            'Team 1', 'Team 2',
+            'Team 3', 'Team 4',
+            'Team 5', 'Team 6',
+            'Team 7', 'Team 8',
+        ]);
+
+        await manager.update.match({
+            id: 0, // WB 1.1
+            opponent1: { score: 1, result: 'win' },
+            opponent2: { score: 0 },
+        });
+
+        await manager.update.match({
+            id: 1, // WB 1.2
+            opponent1: { score: 1, result: 'win' },
+            opponent2: { score: 0 },
+        });
+
+        // This will archive matches 0 and 1.
+        await manager.update.match({
+            id: 4, // WB Semi 1
+            opponent1: { score: 1 },
+            opponent2: { score: 0 },
+        });
+
+        await assert.isRejected(manager.update.seeding(0, [
+            'Team 1', 'Team 2', // Do not even need to change this pair.
+            'Team 3', 'Team 4',
+            'Team 5', 'Team 6',
+            'Team 7', 'Team 8',
+        ]), 'A match of round 1 is archived, which means round 2 was started.');
+    });
+
     it('should throw if a match is locked and would have to be changed', async () => {
         await manager.update.seeding(0, [
             'Team 1', 'Team 2',