diff --git a/backend/packages/Upgrade/src/api/controllers/StratificationController.ts b/backend/packages/Upgrade/src/api/controllers/StratificationController.ts
index d98ed58319..217d067d8e 100644
--- a/backend/packages/Upgrade/src/api/controllers/StratificationController.ts
+++ b/backend/packages/Upgrade/src/api/controllers/StratificationController.ts
@@ -304,7 +304,7 @@ export class StratificationController {
   @UseBefore(upload.single('file'))
   public insertStratification(@Req() request: AppRequest): Promise<UserStratificationFactor[]> {
     const csvData = request.body[0].file;
-    const rows = csvData.split('\n');
+    const rows = csvData.replace(/"/g, '').split('\n');
     const columnNames = rows[0].split(',');
 
     const userFactorValues: StratificationInputValidator[] = [];
diff --git a/backend/packages/Upgrade/src/api/models/Experiment.ts b/backend/packages/Upgrade/src/api/models/Experiment.ts
index d5b03ccbe1..80d18e0f16 100644
--- a/backend/packages/Upgrade/src/api/models/Experiment.ts
+++ b/backend/packages/Upgrade/src/api/models/Experiment.ts
@@ -130,6 +130,7 @@ export class Experiment extends BaseModel {
 
   @ManyToOne(() => StratificationFactor, (stratificationFactor) => stratificationFactor.experiment, {
     onDelete: 'CASCADE',
+    nullable: true,
   })
   public stratificationFactor: StratificationFactor;
 
diff --git a/backend/packages/Upgrade/src/api/services/ExperimentService.ts b/backend/packages/Upgrade/src/api/services/ExperimentService.ts
index c780ddd9cf..19ab0138db 100644
--- a/backend/packages/Upgrade/src/api/services/ExperimentService.ts
+++ b/backend/packages/Upgrade/src/api/services/ExperimentService.ts
@@ -709,7 +709,7 @@ export class ExperimentService {
         } = experiment;
 
         // create stratificationFactor is not found
-        if (!expDoc.stratificationFactor.id) {
+        if (expDoc.stratificationFactor.id) {
           expDoc.stratificationFactor.id = uuid();
           await transactionalEntityManager.getRepository(StratificationFactor).save(expDoc.stratificationFactor);
         }
@@ -1141,7 +1141,7 @@ export class ExperimentService {
       this.checkConditionCodeDefault(conditions);
 
       // create stratificationFactor is not found
-      if (!expDoc.stratificationFactor.id) {
+      if (expDoc.stratificationFactor.id) {
         expDoc.stratificationFactor.id = uuid();
         await transactionalEntityManager.getRepository(StratificationFactor).save(expDoc.stratificationFactor);
       }