diff --git a/src/client/client.service.ts b/src/client/client.service.ts
index 6c20a7c..73f4d08 100644
--- a/src/client/client.service.ts
+++ b/src/client/client.service.ts
@@ -114,6 +114,7 @@ export class ClientService {
   ) {}
   async addClient(client: ClientDto): Promise<ClientDtoRs> {
     try {
+      const smsApiKey = client.property?.smsApiKey?.trim();
       const newClient = await this.clientDbService.create({
         clientCode: client.clientCode,
 
@@ -129,9 +130,7 @@ export class ClientService {
               : (client.clientName?.english ?? null),
         },
 
-        property: {
-          smsApiKey: client.property?.smsApiKey ?? null,
-        },
+        ...(smsApiKey ? { property: { smsApiKey } } : {}),
 
         useExpertMode: client.useExpertMode ?? null,
       });
diff --git a/src/client/dto/create-client.dto.ts b/src/client/dto/create-client.dto.ts
index 9a25ef0..5e21fcc 100644
--- a/src/client/dto/create-client.dto.ts
+++ b/src/client/dto/create-client.dto.ts
@@ -23,8 +23,9 @@ class ClientName {
 }
 class Property {
   @ApiPropertyOptional({})
+  @IsOptional()
   @IsString()
-  smsApiKey: string;
+  smsApiKey?: string;
 }
 
 export class ClientDto {
diff --git a/src/client/entities/db-service/client.db.service.ts b/src/client/entities/db-service/client.db.service.ts
index 24978f7..5276d7a 100644
--- a/src/client/entities/db-service/client.db.service.ts
+++ b/src/client/entities/db-service/client.db.service.ts
@@ -1,15 +1,49 @@
-import { Injectable } from "@nestjs/common";
+import { Injectable, Logger, OnModuleInit } from "@nestjs/common";
 import { InjectModel } from "@nestjs/mongoose";
 import { FilterQuery, Model, UpdateQuery } from "mongoose";
 import { ClientModel, ClientDocument } from "../schema/client.schema";
 
 @Injectable()
-export class ClientDbService {
+export class ClientDbService implements OnModuleInit {
+  private readonly logger = new Logger(ClientDbService.name);
+
   constructor(
     @InjectModel(ClientModel.name)
     private readonly clientModel: Model<ClientModel>,
   ) {}
 
+  async onModuleInit(): Promise<void> {
+    await this.dropLegacyPropertyUniqueIndex();
+  }
+
+  /**
+   * `property` was once declared `unique: true` in the schema. Production keeps
+   * `autoIndex: false`, so the stale unique index remained and rejected a second
+   * client with a missing/null SMS key (E11000 duplicate key).
+   */
+  private async dropLegacyPropertyUniqueIndex(): Promise<void> {
+    try {
+      const indexes = await this.clientModel.collection.indexes();
+      for (const index of indexes) {
+        if (!index.unique || !index.name || index.name === "_id_") continue;
+
+        const keys = Object.keys(index.key ?? {});
+        const isLegacyPropertyIndex =
+          keys.length === 1 &&
+          (keys[0] === "property" || keys[0] === "property.smsApiKey");
+
+        if (!isLegacyPropertyIndex) continue;
+
+        await this.clientModel.collection.dropIndex(index.name);
+        this.logger.warn(
+          `Dropped legacy unique index on clients.${keys[0]}: ${index.name}`,
+        );
+      }
+    } catch (err) {
+      this.logger.error("Failed to drop legacy client property index", err);
+    }
+  }
+
   async create(client: ClientModel): Promise<ClientModel> {
     return await this.clientModel.create(client);
   }
diff --git a/src/client/entities/schema/client.schema.ts b/src/client/entities/schema/client.schema.ts
index 1e11d52..ec79296 100644
--- a/src/client/entities/schema/client.schema.ts
+++ b/src/client/entities/schema/client.schema.ts
@@ -96,9 +96,9 @@ export class ClientModel {
     english: string;
   };
 
-  @Prop({ required: false, unique: false, type: Object })
-  property: {
-    smsApiKey: string;
+  @Prop({ required: false, type: Object })
+  property?: {
+    smsApiKey?: string;
   };
 
   @Prop({ required: true, unique: false })
diff --git a/src/request-management/request-management.service.ts b/src/request-management/request-management.service.ts
index 5d94ddf..70f6f59 100644
--- a/src/request-management/request-management.service.ts
+++ b/src/request-management/request-management.service.ts
@@ -4061,9 +4061,6 @@ export class RequestManagementService {
               persian: data.clientName,
               english: null,
             },
-            property: {
-              smsApiKey: null,
-            },
             useExpertMode: "genuine",
           });
         } catch (err) {
diff --git a/src/sand-hub/sand-hub.service.ts b/src/sand-hub/sand-hub.service.ts
index 3df17c4..99d342b 100644
--- a/src/sand-hub/sand-hub.service.ts
+++ b/src/sand-hub/sand-hub.service.ts
@@ -20,6 +20,9 @@ import { firstValueFrom } from "rxjs";
 
 @Injectable()
 export class SandHubService {
+  private static readonly ESG_INQUIRY_UNAVAILABLE_MESSAGE =
+    "استعلام در دسترس نیست";
+
   private readonly logger = new Logger(SandHubService.name);
   private loginToken: string | null = null;
   private tokenExpiry: Date | null = null;
@@ -528,17 +531,13 @@ export class SandHubService {
     if (!raw) return raw;
 
     if (raw?.success === false) {
+      this.logger.warn(
+        "ESG policyByPlate inquiry returned success=false",
+        raw,
+      );
       return {
         Error: {
-          Message:
-            raw?.error?.message ||
-            raw?.message ||
-            "ESG policyByPlate inquiry returned an error",
-          Code: raw?.error?.code || raw?.error?.providerCode || "ESG_INQUIRY_ERROR",
-          ProviderMessage: raw?.error?.providerMessage,
-          ProviderCode: raw?.error?.providerCode,
-          TrackingCode: raw?.trackingCode,
-          Conflict: raw?.error?.conflict,
+          Message: SandHubService.ESG_INQUIRY_UNAVAILABLE_MESSAGE,
         },
       };
     }
@@ -622,10 +621,9 @@ export class SandHubService {
 
   private mapEsgPersonInquiryToOldFormat(raw: any): Record<string, unknown> {
     if (raw?.success === false) {
-      throw new NotFoundException(
-        raw?.error?.message ||
-          raw?.message ||
-          "Personal inquiry failed: Record not found for the given national code and birth date.",
+      this.logger.warn("ESG person inquiry returned success=false", raw);
+      throw new BadRequestException(
+        SandHubService.ESG_INQUIRY_UNAVAILABLE_MESSAGE,
       );
     }
 
@@ -648,10 +646,9 @@ export class SandHubService {
 
   private mapEsgShebaInquiryToOldFormat(raw: any): Record<string, unknown> {
     if (raw?.success === false) {
+      this.logger.warn("ESG sheba inquiry returned success=false", raw);
       throw new BadRequestException(
-        raw?.error?.message ||
-          raw?.message ||
-          "Sheba ID validation failed. The provided Sheba ID does not match the national ID.",
+        SandHubService.ESG_INQUIRY_UNAVAILABLE_MESSAGE,
       );
     }