diff --git a/modules/services/event-history-service/src/main/java/com/lingniu/ingest/eventhistory/ApiExceptionHandler.java b/modules/services/event-history-service/src/main/java/com/lingniu/ingest/eventhistory/ApiExceptionHandler.java
index e6afa433..45f7b4d7 100644
--- a/modules/services/event-history-service/src/main/java/com/lingniu/ingest/eventhistory/ApiExceptionHandler.java
+++ b/modules/services/event-history-service/src/main/java/com/lingniu/ingest/eventhistory/ApiExceptionHandler.java
@@ -8,7 +8,9 @@ import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
 import org.springframework.web.server.ResponseStatusException;
+import org.springframework.web.servlet.resource.NoResourceFoundException;
 
+import java.io.IOException;
 import java.time.OffsetDateTime;
 import java.time.ZoneId;
 import java.time.format.DateTimeParseException;
@@ -69,6 +71,18 @@ public final class ApiExceptionHandler {
         return error(HttpStatus.BAD_REQUEST, "invalid date/time parameter: " + ex.getParsedString(), request);
     }
 
+    @ExceptionHandler(NoResourceFoundException.class)
+    public ResponseEntity<ApiError> noResource(NoResourceFoundException ex,
+                                               HttpServletRequest request) {
+        return error(HttpStatus.NOT_FOUND, "resource not found: " + request.getRequestURI(), request);
+    }
+
+    @ExceptionHandler(IOException.class)
+    public ResponseEntity<ApiError> io(IOException ex,
+                                       HttpServletRequest request) {
+        return error(HttpStatus.SERVICE_UNAVAILABLE, safeMessage(ex, "history storage unavailable"), request);
+    }
+
     @ExceptionHandler(Exception.class)
     public ResponseEntity<ApiError> generic(Exception ex,
                                             HttpServletRequest request) {
diff --git a/modules/services/event-history-service/src/test/java/com/lingniu/ingest/eventhistory/ApiExceptionHandlerTest.java b/modules/services/event-history-service/src/test/java/com/lingniu/ingest/eventhistory/ApiExceptionHandlerTest.java
index e118593b..b34710fe 100644
--- a/modules/services/event-history-service/src/test/java/com/lingniu/ingest/eventhistory/ApiExceptionHandlerTest.java
+++ b/modules/services/event-history-service/src/test/java/com/lingniu/ingest/eventhistory/ApiExceptionHandlerTest.java
@@ -3,14 +3,22 @@ package com.lingniu.ingest.eventhistory;
 import com.lingniu.ingest.eventfilestore.EventFileStore;
 import com.lingniu.ingest.eventfilestore.EventFileRecord;
 import com.lingniu.ingest.protocol.gb32960.codec.Gb32960MessageDecoder;
+import jakarta.servlet.http.HttpServletRequest;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
+import org.springframework.http.HttpMethod;
 import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.servlet.resource.NoResourceFoundException;
 
+import java.io.IOException;
 import java.nio.file.Path;
 import java.util.List;
 
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
@@ -52,6 +60,32 @@ class ApiExceptionHandlerTest {
                 .andExpect(jsonPath("$.message").value("vin is required for gb32960 snapshots"));
     }
 
+    @Test
+    void ioExceptionReturnsServiceUnavailable() throws Exception {
+        MockMvc mvc = standaloneSetup(new IoFailureController())
+                .setControllerAdvice(new ApiExceptionHandler())
+                .build();
+
+        mvc.perform(get("/io"))
+                .andExpect(status().isServiceUnavailable())
+                .andExpect(jsonPath("$.message").value("tdengine history query failed"))
+                .andExpect(jsonPath("$.path").value("/io"));
+    }
+
+    @Test
+    void noResourceReturnsNotFound() {
+        HttpServletRequest request = mock(HttpServletRequest.class);
+        when(request.getRequestURI()).thenReturn("/missing");
+
+        var response = new ApiExceptionHandler().noResource(
+                new NoResourceFoundException(HttpMethod.GET, "/missing"),
+                request);
+
+        assertThat(response.getStatusCode().value()).isEqualTo(404);
+        assertThat(response.getBody()).isNotNull();
+        assertThat(response.getBody().message()).isEqualTo("resource not found: /missing");
+    }
+
     private Gb32960DecodedFrameService service() {
         EventFileStore store = new EventFileStore() {
             @Override
@@ -69,4 +103,12 @@ class ApiExceptionHandlerTest {
                 archiveRoot,
                 null);
     }
+
+    @RestController
+    private static final class IoFailureController {
+        @GetMapping("/io")
+        String io() throws IOException {
+            throw new IOException("tdengine history query failed");
+        }
+    }
 }