diff --git a/test/api/v3/integration/quests/POST-groups_groupId_quests_accept.test.js b/test/api/v3/integration/quests/POST-groups_groupId_quests_accept.test.js
index d827659108..a07862b0f5 100644
--- a/test/api/v3/integration/quests/POST-groups_groupId_quests_accept.test.js
+++ b/test/api/v3/integration/quests/POST-groups_groupId_quests_accept.test.js
@@ -91,6 +91,23 @@ describe('POST /groups/:groupId/quests/accept', () => {
       expect(partyMembers[0].party.quest.RSVPNeeded).to.be.false;
     });
 
+    it('heals stuck RSVPNeeded when group already has the user accepted', async () => {
+      await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
+      await partyMembers[0].post(`/groups/${questingGroup._id}/quests/accept`);
+
+      await partyMembers[0].updateOne({ 'party.quest.RSVPNeeded': true });
+      await partyMembers[0].sync();
+      expect(partyMembers[0].party.quest.RSVPNeeded).to.be.true;
+
+      const res = await partyMembers[0].post(`/groups/${questingGroup._id}/quests/accept`);
+      expect(res).to.exist;
+
+      await partyMembers[0].sync();
+      await questingGroup.sync();
+      expect(partyMembers[0].party.quest.RSVPNeeded).to.equal(false);
+      expect(questingGroup.quest.members[partyMembers[0]._id]).to.equal(true);
+    });
+
     it('does not accept invite for a quest already underway', async () => {
       await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
       await partyMembers[0].post(`/groups/${questingGroup._id}/quests/accept`);
diff --git a/test/api/v3/integration/quests/POST-groups_groupid_quests_reject.test.js b/test/api/v3/integration/quests/POST-groups_groupid_quests_reject.test.js
index 80b7f27ee0..b2a659c415 100644
--- a/test/api/v3/integration/quests/POST-groups_groupid_quests_reject.test.js
+++ b/test/api/v3/integration/quests/POST-groups_groupid_quests_reject.test.js
@@ -100,6 +100,23 @@ describe('POST /groups/:groupId/quests/reject', () => {
       expect(partyMembers[0].party.quest.RSVPNeeded).to.be.false;
     });
 
+    it('heals stuck RSVPNeeded when group already has the user rejected', async () => {
+      await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
+      await partyMembers[0].post(`/groups/${questingGroup._id}/quests/reject`);
+
+      await partyMembers[0].updateOne({ 'party.quest.RSVPNeeded': true });
+      await partyMembers[0].sync();
+      expect(partyMembers[0].party.quest.RSVPNeeded).to.be.true;
+
+      const res = await partyMembers[0].post(`/groups/${questingGroup._id}/quests/reject`);
+      expect(res).to.exist;
+
+      await partyMembers[0].sync();
+      await questingGroup.sync();
+      expect(partyMembers[0].party.quest.RSVPNeeded).to.equal(false);
+      expect(questingGroup.quest.members[partyMembers[0]._id]).to.equal(false);
+    });
+
     it('return an error when a user rejects an invite already accepted', async () => {
       await leader.post(`/groups/${questingGroup._id}/quests/invite/${PET_QUEST}`);
       await partyMembers[0].post(`/groups/${questingGroup._id}/quests/accept`);
diff --git a/website/server/controllers/api-v3/quests.js b/website/server/controllers/api-v3/quests.js
index 1e46a8744f..d580c126b3 100644
--- a/website/server/controllers/api-v3/quests.js
+++ b/website/server/controllers/api-v3/quests.js
@@ -198,16 +198,32 @@ api.acceptQuest = {
     if (group.type !== 'party') throw new NotAuthorized(res.t('guildQuestsNotSupported'));
     if (!group.quest.key) throw new NotFound(res.t('questInviteNotFound'));
     if (group.quest.active) throw new NotAuthorized(res.t('questAlreadyStartedFriendly'));
-    if (group.quest.members[user._id]) throw new BadRequest(res.t('questAlreadyAccepted'));
 
-    const acceptedSuccessfully = await group.handleQuestInvitation(user, true);
+    if (group.quest.members[user._id] === true) {
+      if (user.party.quest.RSVPNeeded) {
+        user.party.quest.RSVPNeeded = false;
+        await user.save();
+        res.respond(200, group.quest);
+        return;
+      }
+      throw new BadRequest(res.t('questAlreadyAccepted'));
+    }
+    if (group.quest.members[user._id] === false) {
+      throw new BadRequest(res.t('questAlreadyAccepted'));
+    }
+
+    let acceptedSuccessfully = false;
+    await Group.db.transaction(async session => {
+      acceptedSuccessfully = await group.handleQuestInvitation(user, true, session);
+      if (!acceptedSuccessfully) return;
+      user.party.quest.RSVPNeeded = false;
+      await user.save({ session });
+    });
+
     if (!acceptedSuccessfully) {
       throw new NotAuthorized(res.t('questAlreadyAccepted'));
     }
 
-    user.party.quest.RSVPNeeded = false;
-    await user.save();
-
     if (canStartQuestAutomatically(group)) {
       await group.startQuest(user);
     }
@@ -251,18 +267,34 @@ api.rejectQuest = {
     if (group.type !== 'party') throw new NotAuthorized(res.t('guildQuestsNotSupported'));
     if (!group.quest.key) throw new NotFound(res.t('questInvitationDoesNotExist'));
     if (group.quest.active) throw new NotAuthorized(res.t('questAlreadyStartedFriendly'));
-    if (group.quest.members[user._id]) throw new BadRequest(res.t('questAlreadyAccepted'));
-    if (group.quest.members[user._id] === false) throw new BadRequest(res.t('questAlreadyRejected'));
 
-    const rejectedSuccessfully = await group.handleQuestInvitation(user, false);
+    if (group.quest.members[user._id] === true) {
+      throw new BadRequest(res.t('questAlreadyAccepted'));
+    }
+    if (group.quest.members[user._id] === false) {
+      if (user.party.quest.RSVPNeeded) {
+        user.party.quest = Group.cleanQuestUser(user.party.quest.progress);
+        user.markModified('party.quest');
+        await user.save();
+        res.respond(200, group.quest);
+        return;
+      }
+      throw new BadRequest(res.t('questAlreadyRejected'));
+    }
+
+    let rejectedSuccessfully = false;
+    await Group.db.transaction(async session => {
+      rejectedSuccessfully = await group.handleQuestInvitation(user, false, session);
+      if (!rejectedSuccessfully) return;
+      user.party.quest = Group.cleanQuestUser(user.party.quest.progress);
+      user.markModified('party.quest');
+      await user.save({ session });
+    });
+
     if (!rejectedSuccessfully) {
       throw new NotAuthorized(res.t('questAlreadyRejected'));
     }
 
-    user.party.quest = Group.cleanQuestUser(user.party.quest.progress);
-    user.markModified('party.quest');
-    await user.save();
-
     if (canStartQuestAutomatically(group)) {
       await group.startQuest(user);
     }
diff --git a/website/server/models/group.js b/website/server/models/group.js
index 99071d83c7..2517d01162 100644
--- a/website/server/models/group.js
+++ b/website/server/models/group.js
@@ -654,7 +654,8 @@ schema.methods.sendChat = async function sendChat (options = {}) {
   return newChatMessage;
 };
 
-schema.methods.handleQuestInvitation = async function handleQuestInvitation (user, accept) {
+// eslint-disable-next-line max-len
+schema.methods.handleQuestInvitation = async function handleQuestInvitation (user, accept, session) {
   if (!user) throw new InternalServerError('Must provide user to handle quest invitation');
   if (accept !== true && accept !== false) throw new InternalServerError('Must provide accept param handle quest invitation');
 
@@ -662,12 +663,14 @@ schema.methods.handleQuestInvitation = async function handleQuestInvitation (use
   // to prevent multiple concurrent requests overriding updates
   // see https://github.com/HabitRPG/habitica/issues/11398
   const Group = this.constructor;
+  const options = session ? { session } : {};
   const result = await Group.updateOne(
     {
       _id: this._id,
       [`quest.members.${user._id}`]: { $type: 10 }, // match BSON Type Null (type number 10)
     },
     { $set: { [`quest.members.${user._id}`]: accept } },
+    options,
   ).exec();
 
   if (result.modifiedCount) {