diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3da536c66..8d858e89b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 2.5.2 [TODO]
+### Fixed
+- Prevent missing contextual external or previous files from clearing existing contextual data.
+
 ## 2.5.0 [2026-04-16]
 ### Added
 - New schedule endpoints.
diff --git a/src/main/java/fr/insee/genesis/domain/service/contextualvariable/external/ContextualExternalVariableJsonService.java b/src/main/java/fr/insee/genesis/domain/service/contextualvariable/external/ContextualExternalVariableJsonService.java
index f2c835a02..425f1e9cf 100644
--- a/src/main/java/fr/insee/genesis/domain/service/contextualvariable/external/ContextualExternalVariableJsonService.java
+++ b/src/main/java/fr/insee/genesis/domain/service/contextualvariable/external/ContextualExternalVariableJsonService.java
@@ -37,16 +37,19 @@ public ContextualExternalVariableJsonService(ContextualExternalVariablePersistan
     public boolean readContextualExternalFile(String collectionInstrumentId, String filePath) throws GenesisException {
         try(FileInputStream inputStream = new FileInputStream(filePath)){
             JsonFactory jsonFactory = new JsonFactory();
-            moveCollectionToBackup(collectionInstrumentId);
             try(JsonParser jsonParser = jsonFactory.createParser(inputStream)){
-                List<ContextualExternalVariableModel> toSave = new ArrayList<>();
-                goToContextualExternalToken(jsonParser);
-                long savedCount = 0;
-                Set<String> savedInterrogationIds = new HashSet<>();
+                if (!goToContextualExternalToken(jsonParser)) {
+                    log.warn("No contextualExternal part found in file {}", filePath);
+                    return false;
+                }
                 if(jsonParser.nextToken() == null){ //skip field name, stop if end of file
                     log.warn("Reached end of file, found no contextualExternal part.");
                     return false;
                 }
+                moveCollectionToBackup(collectionInstrumentId);
+                List<ContextualExternalVariableModel> toSave = new ArrayList<>();
+                long savedCount = 0;
+                Set<String> savedInterrogationIds = new HashSet<>();
                 jsonParser.nextToken(); //skip [
                 while (jsonParser.currentToken() != JsonToken.END_ARRAY) {
                     ContextualExternalVariableModel contextualExternalVariableModel = readNextContextualExternal(
@@ -84,19 +87,14 @@ public ContextualExternalVariableModel findByCollectionInstrumentIdAndInterrogat
         return contextualExternalVariablePersistancePort.findByCollectionInstrumentIdAndInterrogationId(collectionInstrumentId, interrogationId);
     }
 
-    private static void goToContextualExternalToken(JsonParser jsonParser) throws IOException{
-        boolean isTokenFound = false;
-        while (!isTokenFound){
-            jsonParser.nextToken();
-            if(jsonParser.currentToken() == null){
-                return;
-            }
-            if(jsonParser.currentToken().equals(JsonToken.FIELD_NAME)
-                    && jsonParser.currentName() != null
-                    && jsonParser.currentName().equals("editedExternal")) {
-                    isTokenFound = true;
+    private static boolean goToContextualExternalToken(JsonParser jsonParser) throws IOException {
+        while (jsonParser.nextToken() != null) {
+            if (jsonParser.currentToken() == JsonToken.FIELD_NAME
+                    && "editedExternal".equals(jsonParser.currentName())) {
+                return true;
             }
         }
+        return false;
     }
 
     private void moveCollectionToBackup(String collectionInstrumentId) {
diff --git a/src/main/java/fr/insee/genesis/domain/service/contextualvariable/previous/ContextualPreviousVariableJsonService.java b/src/main/java/fr/insee/genesis/domain/service/contextualvariable/previous/ContextualPreviousVariableJsonService.java
index e8b9b98d8..722e968b6 100644
--- a/src/main/java/fr/insee/genesis/domain/service/contextualvariable/previous/ContextualPreviousVariableJsonService.java
+++ b/src/main/java/fr/insee/genesis/domain/service/contextualvariable/previous/ContextualPreviousVariableJsonService.java
@@ -39,18 +39,22 @@ public boolean readContextualPreviousFile(String collectionInstrumentId,
                                               String filePath) throws GenesisException {
         try(FileInputStream inputStream = new FileInputStream(filePath)){
             checkSourceStateLength(sourceState);
-            moveCollectionToBackup(collectionInstrumentId);
 
             JsonFactory jsonFactory = new JsonFactory();
             try (JsonParser jsonParser = jsonFactory.createParser(inputStream)) {
-                List<ContextualPreviousVariableModel> toSave = new ArrayList<>();
-                goToEditedPreviousToken(jsonParser);
-                long savedCount = 0;
-                Set<String> savedInterrogationIds = new HashSet<>();
+                if (!goToEditedPreviousToken(jsonParser)) {
+                    log.warn("No EditedPrevious part found in file {}", filePath);
+                    return false;
+                }
                 if (jsonParser.nextToken() == null) { //skip field name, stop if end of file
                     log.warn("Reached end of file, found no EditedPrevious part.");
                     return false;
                 }
+                moveCollectionToBackup(collectionInstrumentId);
+                List<ContextualPreviousVariableModel> toSave = new ArrayList<>();
+                long savedCount = 0;
+                Set<String> savedInterrogationIds = new HashSet<>();
+
                 jsonParser.nextToken(); //skip [
                 while (jsonParser.currentToken() != JsonToken.END_ARRAY) {
                     ContextualPreviousVariableModel contextualPreviousVariableModel = readNextContextualPrevious(
@@ -109,19 +113,14 @@ private static void checkSourceStateLength(String sourceState) throws GenesisExc
         }
     }
 
-    private static void goToEditedPreviousToken(JsonParser jsonParser) throws IOException{
-        boolean isTokenFound = false;
-        while (!isTokenFound){
-            jsonParser.nextToken();
-            if(jsonParser.currentToken() == null){
-                return;
-            }
-            if(jsonParser.currentToken().equals(JsonToken.FIELD_NAME)
-                    && jsonParser.currentName() != null
-                    && jsonParser.currentName().equals("editedPrevious")) {
-                    isTokenFound = true;
+    private boolean goToEditedPreviousToken(JsonParser jsonParser) throws IOException {
+        while (jsonParser.nextToken() != null) {
+            if (jsonParser.currentToken() == JsonToken.FIELD_NAME
+                    && "editedPrevious".equals(jsonParser.getCurrentName())) {
+                return true;
             }
         }
+        return false;
     }
 
     private ContextualPreviousVariableModel readNextContextualPrevious(JsonParser jsonParser,