diff --git a/src/core/storage/ISessionConfigRepository.ts b/src/core/storage/ISessionConfigRepository.ts
index f9546dbd..bb5e47fe 100644
--- a/src/core/storage/ISessionConfigRepository.ts
+++ b/src/core/storage/ISessionConfigRepository.ts
@@ -3,7 +3,7 @@ import { SessionConfig } from '../../structures/sessions.dto';
 export abstract class ISessionConfigRepository {
   abstract saveConfig(
     sessionName: string,
-    config: SessionConfig | null,
+    config: SessionConfig,
   ): Promise<void>;
 
   abstract getConfig(sessionName: string): Promise<SessionConfig | null>;
diff --git a/src/core/storage/LocalSessionConfigRepository.ts b/src/core/storage/LocalSessionConfigRepository.ts
index a418e6cb..b17df7d6 100644
--- a/src/core/storage/LocalSessionConfigRepository.ts
+++ b/src/core/storage/LocalSessionConfigRepository.ts
@@ -48,13 +48,13 @@ export class LocalSessionConfigRepository extends ISessionConfigRepository {
     return JSON.parse(content);
   }
 
-  async saveConfig(sessionName: string, config: SessionConfig | null) {
-    // Create folder if not exist
+  async saveConfig(sessionName: string, config: SessionConfig) {
+    // Create a folder if not exist
     const folder = this.store.getSessionDirectory(sessionName);
     await fs.mkdir(folder, { recursive: true });
     // Save config
     const filepath = this.getFilePath(sessionName);
-    const content = JSON.stringify(config || null);
+    const content = JSON.stringify(config || {});
     await writeFileAtomic(filepath, content);
   }
 
diff --git a/src/structures/sessions.dto.ts b/src/structures/sessions.dto.ts
index a96d89d2..a8b7e6c8 100644
--- a/src/structures/sessions.dto.ts
+++ b/src/structures/sessions.dto.ts
@@ -122,7 +122,7 @@ export class SessionConfig {
   })
   @IsBoolean()
   @IsOptional()
-  debug: boolean;
+  debug?: boolean;
 
   @ApiProperty({
     example: {