diff --git a/frontend/src/modules/agent/api/agent.api.service.ts b/frontend/src/modules/agent/api/agent.api.service.ts
index db258e8..906371e 100644
--- a/frontend/src/modules/agent/api/agent.api.service.ts
+++ b/frontend/src/modules/agent/api/agent.api.service.ts
@@ -22,14 +22,14 @@ class AgentApiService {
 
   async getAgents(): Promise<AgentInfo[]> {
     const response = await apiClient.get<AgentInfo[]>(this.basePath);
-    return response.data;
+    return Array.isArray(response.data) ? response.data : [];
   }
 
   async getUsers(): Promise<TokenUser[]> {
     const response = await apiClient.get<TokenUser[]>(
       `${this.authBasePath}/tokens`,
     );
-    return response.data;
+    return Array.isArray(response.data) ? response.data : [];
   }
 
   async createUser(data: TokenCreate): Promise<void> {
@@ -47,15 +47,25 @@ class AgentApiService {
   async searchLogs(filters?: LogFilters): Promise<LogEntry[]> {
     const response = await apiClient.get<LogEntry[]>(this.logsBasePath, {
       params: {
-        level: filters?.level,
-        service: filters?.service,
-        agent: filters?.agent,
-        date_from: filters?.date_from,
-        date_to: filters?.date_to,
+        level: filters?.level || undefined,
+        service: filters?.service || undefined,
+        agent: filters?.agent || undefined,
+        date_from: filters?.date_from || undefined,
+        date_to: filters?.date_to || undefined,
         limit: filters?.limit ?? 100,
         offset: filters?.offset ?? 0,
       },
     });
+
+    if (!Array.isArray(response.data)) {
+      console.error(
+        "[Logs] Unexpected response format:",
+        typeof response.data,
+        response.data,
+      );
+      return [];
+    }
+
     return response.data;
   }
 
@@ -71,21 +81,21 @@ class AgentApiService {
     const response = await apiClient.get<string[]>(
       `${this.logsBasePath}/agents`,
     );
-    return response.data;
+    return Array.isArray(response.data) ? response.data : [];
   }
 
   async getDistinctLevels(): Promise<string[]> {
     const response = await apiClient.get<string[]>(
       `${this.logsBasePath}/levels`,
     );
-    return response.data;
+    return Array.isArray(response.data) ? response.data : [];
   }
 
   async getDistinctServices(): Promise<string[]> {
     const response = await apiClient.get<string[]>(
       `${this.logsBasePath}/services`,
     );
-    return response.data;
+    return Array.isArray(response.data) ? response.data : [];
   }
 
   // User management methods
@@ -93,6 +103,9 @@ class AgentApiService {
     const response = await apiClient.get<TokenUser>(
       `${this.authBasePath}/users/${login}`,
     );
+    if (!response.data || typeof response.data !== "object") {
+      throw new Error(`User not found: ${login}`);
+    }
     return response.data;
   }
 
@@ -100,7 +113,7 @@ class AgentApiService {
     const response = await apiClient.get<TokenUser[]>(
       `${this.authBasePath}/users/inactive`,
     );
-    return response.data;
+    return Array.isArray(response.data) ? response.data : [];
   }
 
   async updateUser(login: string, data: TokenUpdate): Promise<void> {
diff --git a/frontend/src/shared/api/axios.instance.ts b/frontend/src/shared/api/axios.instance.ts
index d61f9fe..afd5aa1 100644
--- a/frontend/src/shared/api/axios.instance.ts
+++ b/frontend/src/shared/api/axios.instance.ts
@@ -22,7 +22,7 @@ class ApiClient {
         "Content-Type": "application/json",
       },
       validateStatus: (status) => {
-        return status >= 200 && status < 500;
+        return status >= 200 && status < 400;
       },
     });