diff --git a/internal/rdb/inspect_test.go b/internal/rdb/inspect_test.go
index b66e86a..fc5d655 100644
--- a/internal/rdb/inspect_test.go
+++ b/internal/rdb/inspect_test.go
@@ -5,7 +5,6 @@
 package rdb
 
 import (
-	"errors"
 	"fmt"
 	"testing"
 	"time"
@@ -15,6 +14,7 @@ import (
 	"github.com/google/uuid"
 	h "github.com/hibiken/asynq/internal/asynqtest"
 	"github.com/hibiken/asynq/internal/base"
+	"github.com/hibiken/asynq/internal/errors"
 )
 
 func TestAllQueues(t *testing.T) {
@@ -1090,8 +1090,8 @@ func TestRunArchivedTask(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedMessages(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortMsgOpt); diff != "" {
+			gotArchived := h.GetArchivedMessages(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortMsgOpt); diff != "" {
 				t.Errorf("mismatch found in %q, (-want, +got)\n%s", base.ArchivedKey(qname), diff)
 			}
 		}
@@ -1610,8 +1610,8 @@ func TestRunAllArchivedTasks(t *testing.T) {
 			}
 		}
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedMessages(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortMsgOpt); diff != "" {
+			gotArchived := h.GetArchivedMessages(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortMsgOpt); diff != "" {
 				t.Errorf("%s; mismatch found in %q; (-want, +got)\n%s", tc.desc, base.ArchivedKey(qname), diff)
 			}
 		}
@@ -1635,7 +1635,6 @@ func TestArchiveRetryTask(t *testing.T) {
 		archived     map[string][]base.Z
 		qname        string
 		id           uuid.UUID
-		want         error
 		wantRetry    map[string][]base.Z
 		wantArchived map[string][]base.Z
 	}{
@@ -1651,7 +1650,6 @@ func TestArchiveRetryTask(t *testing.T) {
 			},
 			qname: "default",
 			id:    m1.ID,
-			want:  nil,
 			wantRetry: map[string][]base.Z{
 				"default": {{Message: m2, Score: t2.Unix()}},
 			},
@@ -1659,23 +1657,6 @@ func TestArchiveRetryTask(t *testing.T) {
 				"default": {{Message: m1, Score: time.Now().Unix()}},
 			},
 		},
-		{
-			retry: map[string][]base.Z{
-				"default": {{Message: m1, Score: t1.Unix()}},
-			},
-			archived: map[string][]base.Z{
-				"default": {{Message: m2, Score: t2.Unix()}},
-			},
-			qname: "default",
-			id:    uuid.New(),
-			want:  ErrTaskNotFound,
-			wantRetry: map[string][]base.Z{
-				"default": {{Message: m1, Score: t1.Unix()}},
-			},
-			wantArchived: map[string][]base.Z{
-				"default": {{Message: m2, Score: t2.Unix()}},
-			},
-		},
 		{
 			retry: map[string][]base.Z{
 				"default": {
@@ -1693,7 +1674,6 @@ func TestArchiveRetryTask(t *testing.T) {
 			},
 			qname: "custom",
 			id:    m3.ID,
-			want:  nil,
 			wantRetry: map[string][]base.Z{
 				"default": {
 					{Message: m1, Score: t1.Unix()},
@@ -1715,10 +1695,9 @@ func TestArchiveRetryTask(t *testing.T) {
 		h.SeedAllRetryQueues(t, r.client, tc.retry)
 		h.SeedAllArchivedQueues(t, r.client, tc.archived)
 
-		got := r.ArchiveTask(tc.qname, tc.id)
-		if !errors.Is(got, tc.want) {
-			t.Errorf("(*RDB).ArchiveTask(%q, %v) = %v, want %v",
-				tc.qname, tc.id, got, tc.want)
+		if got := r.ArchiveTask(tc.qname, tc.id); got != nil {
+			t.Errorf("(*RDB).ArchiveTask(%q, %v) returned error: %v",
+				tc.qname, tc.id, got)
 			continue
 		}
 
@@ -1731,8 +1710,8 @@ func TestArchiveRetryTask(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
 					base.ArchivedKey(qname), diff)
 			}
@@ -1757,7 +1736,6 @@ func TestArchiveScheduledTask(t *testing.T) {
 		archived      map[string][]base.Z
 		qname         string
 		id            uuid.UUID
-		want          error
 		wantScheduled map[string][]base.Z
 		wantArchived  map[string][]base.Z
 	}{
@@ -1773,7 +1751,6 @@ func TestArchiveScheduledTask(t *testing.T) {
 			},
 			qname: "default",
 			id:    m1.ID,
-			want:  nil,
 			wantScheduled: map[string][]base.Z{
 				"default": {{Message: m2, Score: t2.Unix()}},
 			},
@@ -1781,40 +1758,6 @@ func TestArchiveScheduledTask(t *testing.T) {
 				"default": {{Message: m1, Score: time.Now().Unix()}},
 			},
 		},
-		{
-			scheduled: map[string][]base.Z{
-				"default": {{Message: m1, Score: t1.Unix()}},
-			},
-			archived: map[string][]base.Z{
-				"default": {{Message: m2, Score: t2.Unix()}},
-			},
-			qname: "nonexistent",
-			id:    m2.ID,
-			want:  ErrQueueNotFound,
-			wantScheduled: map[string][]base.Z{
-				"default": {{Message: m1, Score: t1.Unix()}},
-			},
-			wantArchived: map[string][]base.Z{
-				"default": {{Message: m2, Score: t2.Unix()}},
-			},
-		},
-		{
-			scheduled: map[string][]base.Z{
-				"default": {{Message: m1, Score: t1.Unix()}},
-			},
-			archived: map[string][]base.Z{
-				"default": {{Message: m2, Score: t2.Unix()}},
-			},
-			qname: "default",
-			id:    m2.ID,
-			want:  ErrTaskAlreadyArchived,
-			wantScheduled: map[string][]base.Z{
-				"default": {{Message: m1, Score: t1.Unix()}},
-			},
-			wantArchived: map[string][]base.Z{
-				"default": {{Message: m2, Score: t2.Unix()}},
-			},
-		},
 		{
 			scheduled: map[string][]base.Z{
 				"default": {
@@ -1832,7 +1775,6 @@ func TestArchiveScheduledTask(t *testing.T) {
 			},
 			qname: "custom",
 			id:    m3.ID,
-			want:  nil,
 			wantScheduled: map[string][]base.Z{
 				"default": {
 					{Message: m1, Score: t1.Unix()},
@@ -1854,10 +1796,9 @@ func TestArchiveScheduledTask(t *testing.T) {
 		h.SeedAllScheduledQueues(t, r.client, tc.scheduled)
 		h.SeedAllArchivedQueues(t, r.client, tc.archived)
 
-		got := r.ArchiveTask(tc.qname, tc.id)
-		if !errors.Is(got, tc.want) {
-			t.Errorf("(*RDB).ArchiveTask(%q, %v) = %v, want %v",
-				tc.qname, tc.id, got, tc.want)
+		if got := r.ArchiveTask(tc.qname, tc.id); got != nil {
+			t.Errorf("(*RDB).ArchiveTask(%q, %v) returned error: %v",
+				tc.qname, tc.id, got)
 			continue
 		}
 
@@ -1870,8 +1811,8 @@ func TestArchiveScheduledTask(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
 					base.ArchivedKey(qname), diff)
 			}
@@ -1887,14 +1828,11 @@ func TestArchivePendingTask(t *testing.T) {
 	m3 := h.NewTaskMessageWithQueue("task3", nil, "custom")
 	m4 := h.NewTaskMessageWithQueue("task4", nil, "custom")
 
-	oneHourAgo := time.Now().Add(-1 * time.Hour)
-
 	tests := []struct {
 		pending      map[string][]*base.TaskMessage
 		archived     map[string][]base.Z
 		qname        string
 		id           uuid.UUID
-		want         error
 		wantPending  map[string][]*base.TaskMessage
 		wantArchived map[string][]base.Z
 	}{
@@ -1907,7 +1845,6 @@ func TestArchivePendingTask(t *testing.T) {
 			},
 			qname: "default",
 			id:    m1.ID,
-			want:  nil,
 			wantPending: map[string][]*base.TaskMessage{
 				"default": {m2},
 			},
@@ -1915,23 +1852,6 @@ func TestArchivePendingTask(t *testing.T) {
 				"default": {{Message: m1, Score: time.Now().Unix()}},
 			},
 		},
-		{
-			pending: map[string][]*base.TaskMessage{
-				"default": {m1},
-			},
-			archived: map[string][]base.Z{
-				"default": {{Message: m2, Score: oneHourAgo.Unix()}},
-			},
-			qname: "default",
-			id:    uuid.New(),
-			want:  ErrTaskNotFound,
-			wantPending: map[string][]*base.TaskMessage{
-				"default": {m1},
-			},
-			wantArchived: map[string][]base.Z{
-				"default": {{Message: m2, Score: oneHourAgo.Unix()}},
-			},
-		},
 		{
 			pending: map[string][]*base.TaskMessage{
 				"default": {m1, m2},
@@ -1943,7 +1863,6 @@ func TestArchivePendingTask(t *testing.T) {
 			},
 			qname: "custom",
 			id:    m3.ID,
-			want:  nil,
 			wantPending: map[string][]*base.TaskMessage{
 				"default": {m1, m2},
 				"custom":  {m4},
@@ -1960,10 +1879,9 @@ func TestArchivePendingTask(t *testing.T) {
 		h.SeedAllPendingQueues(t, r.client, tc.pending)
 		h.SeedAllArchivedQueues(t, r.client, tc.archived)
 
-		got := r.ArchiveTask(tc.qname, tc.id)
-		if !errors.Is(got, tc.want) {
-			t.Errorf("(*RDB).ArchiveTask(%q, %v) = %v, want %v",
-				tc.qname, tc.id, got, tc.want)
+		if got := r.ArchiveTask(tc.qname, tc.id); got != nil {
+			t.Errorf("(*RDB).ArchiveTask(%q, %v) returned error: %v",
+				tc.qname, tc.id, got)
 			continue
 		}
 
@@ -1976,8 +1894,111 @@ func TestArchivePendingTask(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
+					base.ArchivedKey(qname), diff)
+			}
+		}
+	}
+}
+
+func TestArchiveTaskError(t *testing.T) {
+	r := setup(t)
+	defer r.Close()
+	m1 := h.NewTaskMessage("task1", nil)
+	m2 := h.NewTaskMessage("task2", nil)
+	t1 := time.Now().Add(1 * time.Minute)
+	t2 := time.Now().Add(1 * time.Hour)
+
+	tests := []struct {
+		desc          string
+		scheduled     map[string][]base.Z
+		archived      map[string][]base.Z
+		qname         string
+		id            uuid.UUID
+		match         func(err error) bool
+		wantScheduled map[string][]base.Z
+		wantArchived  map[string][]base.Z
+	}{
+		{
+			desc: "It should return QueueNotFoundError if provided queue name doesn't exist",
+			scheduled: map[string][]base.Z{
+				"default": {{Message: m1, Score: t1.Unix()}},
+			},
+			archived: map[string][]base.Z{
+				"default": {{Message: m2, Score: t2.Unix()}},
+			},
+			qname: "nonexistent",
+			id:    m2.ID,
+			match: errors.IsQueueNotFound,
+			wantScheduled: map[string][]base.Z{
+				"default": {{Message: m1, Score: t1.Unix()}},
+			},
+			wantArchived: map[string][]base.Z{
+				"default": {{Message: m2, Score: t2.Unix()}},
+			},
+		},
+		{
+			desc: "It should return TaskNotFoundError if provided task ID doesn't exist in the queue",
+			scheduled: map[string][]base.Z{
+				"default": {{Message: m1, Score: t1.Unix()}},
+			},
+			archived: map[string][]base.Z{
+				"default": {{Message: m2, Score: t2.Unix()}},
+			},
+			qname: "default",
+			id:    uuid.New(),
+			match: errors.IsTaskNotFound,
+			wantScheduled: map[string][]base.Z{
+				"default": {{Message: m1, Score: t1.Unix()}},
+			},
+			wantArchived: map[string][]base.Z{
+				"default": {{Message: m2, Score: t2.Unix()}},
+			},
+		},
+		{
+			desc: "It should return TaskAlreadyArchivedError if task is already in archived state",
+			scheduled: map[string][]base.Z{
+				"default": {{Message: m1, Score: t1.Unix()}},
+			},
+			archived: map[string][]base.Z{
+				"default": {{Message: m2, Score: t2.Unix()}},
+			},
+			qname: "default",
+			id:    m2.ID,
+			match: errors.IsTaskAlreadyArchived,
+			wantScheduled: map[string][]base.Z{
+				"default": {{Message: m1, Score: t1.Unix()}},
+			},
+			wantArchived: map[string][]base.Z{
+				"default": {{Message: m2, Score: t2.Unix()}},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		h.FlushDB(t, r.client)
+		h.SeedAllScheduledQueues(t, r.client, tc.scheduled)
+		h.SeedAllArchivedQueues(t, r.client, tc.archived)
+
+		got := r.ArchiveTask(tc.qname, tc.id)
+		if !tc.match(got) {
+			t.Errorf("%s: returned error didn't match: got=%v", tc.desc, got)
+			continue
+		}
+
+		for qname, want := range tc.wantScheduled {
+			gotScheduled := h.GetScheduledEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotScheduled, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
+					base.ScheduledKey(qname), diff)
+			}
+		}
+
+		for qname, want := range tc.wantArchived {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
 					base.ArchivedKey(qname), diff)
 			}
@@ -2108,8 +2129,8 @@ func TestArchiveAllPendingTasks(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
 					base.ArchivedKey(qname), diff)
 			}
@@ -2254,8 +2275,8 @@ func TestArchiveAllRetryTasks(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
 					base.ArchivedKey(qname), diff)
 			}
@@ -2401,8 +2422,8 @@ func TestArchiveAllScheduledTasks(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt, zScoreCmpOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want,+got)\n%s",
 					base.ArchivedKey(qname), diff)
 			}
@@ -2497,8 +2518,8 @@ func TestDeleteArchivedTask(t *testing.T) {
 		}
 
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedMessages(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortMsgOpt); diff != "" {
+			gotArchived := h.GetArchivedMessages(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortMsgOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.ArchivedKey(qname), diff)
 			}
 		}
@@ -2791,8 +2812,8 @@ func TestDeleteAllArchivedTasks(t *testing.T) {
 			t.Errorf("r.DeleteAllDeadTasks(%q) = %d, nil, want %d, nil", tc.qname, got, tc.want)
 		}
 		for qname, want := range tc.wantArchived {
-			gotDead := h.GetArchivedMessages(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortMsgOpt); diff != "" {
+			gotArchived := h.GetArchivedMessages(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortMsgOpt); diff != "" {
 				t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.ArchivedKey(qname), diff)
 			}
 		}
@@ -3221,8 +3242,8 @@ func TestRemoveQueueError(t *testing.T) {
 			}
 		}
 		for qname, want := range tc.archived {
-			gotDead := h.GetArchivedEntries(t, r.client, qname)
-			if diff := cmp.Diff(want, gotDead, h.SortZSetEntryOpt); diff != "" {
+			gotArchived := h.GetArchivedEntries(t, r.client, qname)
+			if diff := cmp.Diff(want, gotArchived, h.SortZSetEntryOpt); diff != "" {
 				t.Errorf("%s;mismatch found in %q; (-want,+got):\n%s", tc.desc, base.ArchivedKey(qname), diff)
 			}
 		}
diff --git a/internal/rdb/rdb.go b/internal/rdb/rdb.go
index b122284..4b8f101 100644
--- a/internal/rdb/rdb.go
+++ b/internal/rdb/rdb.go
@@ -23,9 +23,6 @@ var (
 	// ErrTaskNotFound indicates that a task that matches the given identifier was not found.
 	ErrTaskNotFound = fmt.Errorf("%w: could not find a task in the queue", base.ErrNotFound)
 
-	// ErrTaskAlreadyArchived indicates that the task in question is already in archive state.
-	ErrTaskAlreadyArchived = fmt.Errorf("%w: task is already archived", base.ErrFailedPrecondition)
-
 	// ErrDuplicateTask indicates that another task with the same unique key holds the uniqueness lock.
 	ErrDuplicateTask = errors.New("task already exists")