diff --git a/frontend/src/api/gisApi.ts b/frontend/src/api/gisApi.ts
index fd7129d..c1d260a 100644
--- a/frontend/src/api/gisApi.ts
+++ b/frontend/src/api/gisApi.ts
@@ -51,7 +51,7 @@ export const gisApi = {
   },
 
   getVesselTracks(mmsiList: string[], startTime: string, endTime: string): Promise<VesselTrackResult[]> {
-    return postJson('/api/v2/tracks/vessels', { mmsiList, startTime, endTime })
+    return postJson('/api/v2/tracks/vessels', { vessels: mmsiList, startTime, endTime })
   },
 
   getRecentPositions(minutes = 10): Promise<RecentPosition[]> {
diff --git a/frontend/src/features/viewport-replay/components/ReplaySetupPanel.tsx b/frontend/src/features/viewport-replay/components/ReplaySetupPanel.tsx
index d4c4199..a102561 100644
--- a/frontend/src/features/viewport-replay/components/ReplaySetupPanel.tsx
+++ b/frontend/src/features/viewport-replay/components/ReplaySetupPanel.tsx
@@ -40,9 +40,10 @@ export default function ReplaySetupPanel({ map }: ReplaySetupPanelProps) {
   const handleQuery = () => {
     if (!map) return
     const bounds = getViewportBounds(map)
-    const zoom = map.getZoom()
-    const startISO = startTime.replace('T', ' ') + ':00'
-    const endISO = endTime.replace('T', ' ') + ':00'
+    const zoom = Math.round(map.getZoom())
+    // 백엔드 @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ss") 형식 유지
+    const startISO = startTime + ':00'
+    const endISO = endTime + ':00'
     replayWebSocket.executeQuery(startISO, endISO, bounds, zoom)
   }
 
diff --git a/frontend/src/features/viewport-replay/services/replayWebSocket.ts b/frontend/src/features/viewport-replay/services/replayWebSocket.ts
index cc47c16..1be5ae6 100644
--- a/frontend/src/features/viewport-replay/services/replayWebSocket.ts
+++ b/frontend/src/features/viewport-replay/services/replayWebSocket.ts
@@ -94,12 +94,16 @@ class ReplayWebSocketService {
         },
 
         onStompError: (frame) => {
-          console.error('[ReplayWS] STOMP error:', frame.headers.message)
+          console.error('[ReplayWS] STOMP error:', frame.headers.message, frame.body)
+          if (replayStore.querying) {
+            replayStore.completeQuery()
+          }
           replayStore.setConnectionState('error')
           reject(new Error(frame.headers.message))
         },
 
-        onWebSocketError: () => {
+        onWebSocketError: (evt) => {
+          console.error('[ReplayWS] WebSocket error:', evt)
           replayStore.setConnectionState('error')
           reject(new Error('WebSocket connection failed'))
         },
@@ -158,6 +162,7 @@ class ReplayWebSocketService {
       zoomLevel,
     }
 
+    console.log('[ReplayWS] Sending query:', request.startTime, '~', request.endTime, 'zoom:', request.zoomLevel)
     this.client.publish({
       destination: '/app/tracks/query',
       body: JSON.stringify(request),
@@ -196,9 +201,15 @@ class ReplayWebSocketService {
     this.client.subscribe('/user/queue/tracks/response', (msg: IMessage) => {
       try {
         const data = JSON.parse(msg.body)
+        console.log('[ReplayWS] Response:', data.status, data.queryId)
         if (data.queryId) {
           this.currentQueryId = data.queryId
         }
+        if (data.status === 'ERROR') {
+          console.error('[ReplayWS] Query error:', data.message)
+          this.clearQueryTimeout()
+          useReplayStore.getState().completeQuery()
+        }
       } catch { /* ignore */ }
     })
   }