diff --git a/csst_common/data_manager.py b/csst_common/data_manager.py
index d6cab3509c61f7c357b7b25a3a5b1c9ef0f9a9fb..4c42cec974ebebea6713e5488a09a53c1d8c94e0 100644
--- a/csst_common/data_manager.py
+++ b/csst_common/data_manager.py
@@ -463,7 +463,8 @@ class CsstMsDataManager:
         assert detector in self.available_detectors
         fn = f"{self.instrument}_{self.obs_id}_chip_{detector:02d}_filt_{self.detector2filter[detector]}.cat"
         fp = os.path.join(self.dir_l0, fn)
-        assert os.path.exists(fp)
+        if not os.path.exists(fp):
+            raise FileNotFoundError(f"File not found: {fp}")
         return fp
 
     def l0_log(self, detector=6):
@@ -471,7 +472,8 @@ class CsstMsDataManager:
         assert detector in self.available_detectors
         fn = f"{self.instrument}_{self.obs_id}_chip_{detector:02d}_filt_{self.detector2filter[detector]}.log"
         fp = os.path.join(self.dir_l0, fn)
-        assert os.path.exists(fp)
+        if not os.path.exists(fp):
+            raise FileNotFoundError(f"File not found: {fp}")
         return fp
 
     def l0_detector(self, detector=6):
@@ -484,8 +486,9 @@ class CsstMsDataManager:
             fn = f"{self.telescope}_{self.instrument}_{self.project}_{self.obs_type}_{self.exp_start}_" \
                  f"{self.exp_stop}_{self.obs_id}_{detector:02d}_L{self.level}_V{self.version}.{self.ext}"
         fp = os.path.join(self.dir_l0, fn)
-        assert os.path.exists(fp)
-        return os.path.join(self.dir_l0, fn)
+        if not os.path.exists(fp):
+            raise FileNotFoundError(f"File not found: {fp}")
+        return fp
 
     def l0_crs(self, detector=6):
         """ L0 cosmic ray file path """
@@ -497,8 +500,9 @@ class CsstMsDataManager:
             fn = f"{self.telescope}_{self.instrument}_{self.project}_CRS_{self.exp_start}_" \
                  f"{self.exp_stop}_{self.obs_id}_{detector:02d}_L{self.level}_V{self.version}.{self.ext}"
         fp = os.path.join(self.dir_l0, fn)
-        assert os.path.exists(fp)
-        return os.path.join(self.dir_l0, fn)
+        if not os.path.exists(fp):
+            raise FileNotFoundError(f"File not found: {fp}")
+        return fp
 
     def l1_detector(self, detector=6, post="IMG.fits"):
         """ generate L1 file path