diff --git a/apps/server/src/modules/monitor/errs.go b/apps/server/src/modules/monitor/errs.go
new file mode 100644
index 00000000..c5d8df19
--- /dev/null
+++ b/apps/server/src/modules/monitor/errs.go
@@ -0,0 +1,11 @@
+package monitor
+
+import "errors"
+
+var (
+	ErrNotFound = errors.New("not found")
+)
+
+var (
+	ErrMonitorNotFound = errors.New("monitor not found")
+)
diff --git a/apps/server/src/modules/monitor/monitor.controller.go b/apps/server/src/modules/monitor/monitor.controller.go
index 43109a20..5e48f673 100644
--- a/apps/server/src/modules/monitor/monitor.controller.go
+++ b/apps/server/src/modules/monitor/monitor.controller.go
@@ -1,6 +1,7 @@
 package monitor
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"peekaping/src/modules/monitor_notification"
@@ -285,6 +286,10 @@ func (ic *MonitorController) UpdateFull(ctx *gin.Context) {
 	updatedMonitor, err := ic.monitorService.UpdateFull(ctx, id, &monitor)
 	if err != nil {
 		ic.logger.Errorw("Failed to update monitor", "error", err)
+		if errors.Is(err, ErrMonitorNotFound) {
+			ctx.JSON(http.StatusNotFound, utils.NewFailResponse(err.Error()))
+			return
+		}
 		ctx.JSON(http.StatusInternalServerError, utils.NewFailResponse("Internal server error"))
 		return
 	}
diff --git a/apps/server/src/modules/monitor/monitor.mongo.repository.go b/apps/server/src/modules/monitor/monitor.mongo.repository.go
index 92b7e0dd..e413ff65 100644
--- a/apps/server/src/modules/monitor/monitor.mongo.repository.go
+++ b/apps/server/src/modules/monitor/monitor.mongo.repository.go
@@ -3,6 +3,7 @@ package monitor
 import (
 	"context"
 	"errors"
+	"fmt"
 	"peekaping/src/config"
 	"peekaping/src/modules/heartbeat"
 	"time"
@@ -385,6 +386,9 @@ func (r *MonitorRepositoryImpl) UpdateFull(ctx context.Context, id string, monit
 	if err != nil {
 		return err
 	}
+	if existingMonitor == nil {
+		return fmt.Errorf("%w: monitor %s", ErrMonitorNotFound, id)
+	}
 
 	filter := bson.M{"_id": objectID}
 	update := bson.M{}
diff --git a/apps/server/src/modules/monitor/monitor.sql.repository.go b/apps/server/src/modules/monitor/monitor.sql.repository.go
index 5da19c24..ae70b892 100644
--- a/apps/server/src/modules/monitor/monitor.sql.repository.go
+++ b/apps/server/src/modules/monitor/monitor.sql.repository.go
@@ -2,6 +2,7 @@ package monitor
 
 import (
 	"context"
+	"fmt"
 	"time"
 
 	"peekaping/src/modules/shared"
@@ -209,11 +210,25 @@ func (r *SQLRepositoryImpl) UpdateFull(ctx context.Context, id string, monitor *
 	sm := toSQLModel(monitor)
 	sm.UpdatedAt = time.Now()
 
-	_, err := r.db.NewUpdate().
+	result, err := r.db.NewUpdate().
 		Model(sm).
 		Where("id = ?", id).
 		ExcludeColumn("id", "created_at").
 		Exec(ctx)
+
+	if err != nil {
+		return err
+	}
+
+	rowAffected, err := result.RowsAffected()
+	if err != nil {
+		return err
+	}
+
+	if rowAffected == 0 {
+		return fmt.Errorf("%w: monitor %s", ErrMonitorNotFound, id)
+	}
+
 	return err
 }