diff --git a/src/lib/antigravity/QuotaService.ts b/src/lib/antigravity/QuotaService.ts
index 467fd41..e40dbfd 100644
--- a/src/lib/antigravity/QuotaService.ts
+++ b/src/lib/antigravity/QuotaService.ts
@@ -126,7 +126,12 @@ export class QuotaService {
       } catch (error: any) {
         if (axios.isAxiosError(error)) {
           const status = error.response?.status;
-          const text = JSON.stringify(error.response?.data || '');
+          let text = '';
+          try {
+            text = JSON.stringify(error.response?.data || '');
+          } catch {
+            text = '[Unable to serialize response data]';
+          }
 
           // ✅ Handle 403 Forbidden specifically - return immediately, do not retry
           if (status === 403) {
diff --git a/src/main.ts b/src/main.ts
index 34f9432..b3be982 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -20,9 +20,28 @@ import { ConfigManager } from './ipc/config/manager';
 
 const packetLogPath = path.join(app.getPath('userData'), 'orpc_packets.log');
 
+/**
+ * Safely stringify an object, handling circular references
+ */
+function safeStringifyPacket(obj: unknown): string {
+  const seen = new WeakSet();
+  return JSON.stringify(obj, (key, value) => {
+    if (typeof value === 'object' && value !== null) {
+      if (seen.has(value)) {
+        return '[Circular]';
+      }
+      seen.add(value);
+    }
+    return value;
+  });
+}
+
 function logPacket(data: any) {
   try {
-    fs.appendFileSync(packetLogPath, `[${new Date().toISOString()}] ${JSON.stringify(data)}\n`);
+    fs.appendFileSync(
+      packetLogPath,
+      `[${new Date().toISOString()}] ${safeStringifyPacket(data)}\n`,
+    );
   } catch (e) {
     if (e instanceof Error) {
       console.error(e.message);
diff --git a/src/server/modules/proxy/clients/gemini.client.ts b/src/server/modules/proxy/clients/gemini.client.ts
index c5b6721..fd6af6b 100644
--- a/src/server/modules/proxy/clients/gemini.client.ts
+++ b/src/server/modules/proxy/clients/gemini.client.ts
@@ -27,7 +27,8 @@ export class GeminiClient {
         this.logger.error(`Gemini Stream API Error: ${error.message}`);
         throw new Error(error.response?.data?.error?.message || error.message);
       }
-      throw error;
+      // Re-throw as clean Error to avoid circular reference issues
+      throw error instanceof Error ? new Error(error.message) : new Error(String(error));
     }
   }
 
@@ -50,11 +51,12 @@ export class GeminiClient {
     } catch (error) {
       if (axios.isAxiosError(error)) {
         this.logger.error(
-          `Gemini API Error: ${error.message} - ${JSON.stringify(error.response?.data)}`,
+          `Gemini API Error: ${error.message} - ${this.safeStringify(error.response?.data)}`,
         );
         throw new Error(error.response?.data?.error?.message || error.message);
       }
-      throw error;
+      // Re-throw as clean Error to avoid circular reference issues
+      throw error instanceof Error ? new Error(error.message) : new Error(String(error));
     }
   }
 
@@ -77,7 +79,6 @@ export class GeminiClient {
       return response.data;
     } catch (error) {
       this.handleAxiosError(error, 'StreamInternal');
-      throw error;
     }
   }
 
@@ -96,17 +97,38 @@ export class GeminiClient {
       return response.data.response || response.data;
     } catch (error) {
       this.handleAxiosError(error, 'GenerateInternal');
-      throw error;
     }
   }
 
   private handleAxiosError(error: any, context: string) {
     if (axios.isAxiosError(error)) {
       this.logger.error(
-        `Gemini ${context} API Error: ${error.message} - ${JSON.stringify(error.response?.data)}`,
+        `Gemini ${context} API Error: ${error.message} - ${this.safeStringify(error.response?.data)}`,
       );
       throw new Error(error.response?.data?.error?.message || error.message);
     }
-    throw error;
+    // Re-throw as clean Error to avoid circular reference issues
+    throw error instanceof Error ? new Error(error.message) : new Error(String(error));
+  }
+
+  /**
+   * Safely stringify an object, handling circular references
+   */
+  private safeStringify(obj: unknown): string {
+    if (obj === undefined || obj === null) {
+      return String(obj);
+    }
+    try {
+      const seen = new WeakSet();
+      return JSON.stringify(obj, (key, value) => {
+        if (typeof value === 'object' && value !== null) {
+          if (seen.has(value)) return '[Circular]';
+          seen.add(value);
+        }
+        return value;
+      });
+    } catch {
+      return '[Unserializable]';
+    }
   }
 }
diff --git a/src/server/modules/proxy/proxy.service.ts b/src/server/modules/proxy/proxy.service.ts
index 7313722..7d1ed4b 100644
--- a/src/server/modules/proxy/proxy.service.ts
+++ b/src/server/modules/proxy/proxy.service.ts
@@ -217,7 +217,11 @@ export class ProxyService {
         subscriber.complete();
       });
 
-      upstreamStream.on('error', (err: any) => subscriber.error(err));
+      upstreamStream.on('error', (err: any) => {
+        // Convert to clean Error to avoid circular reference issues (socket objects)
+        const cleanError = err instanceof Error ? new Error(err.message) : new Error(String(err));
+        subscriber.error(cleanError);
+      });
     });
   }
 
@@ -372,7 +376,9 @@ export class ProxyService {
       });
 
       upstreamStream.on('error', (err: any) => {
-        subscriber.error(err);
+        // Convert to clean Error to avoid circular reference issues (socket objects)
+        const cleanError = err instanceof Error ? new Error(err.message) : new Error(String(err));
+        subscriber.error(cleanError);
       });
     });
   }
diff --git a/src/utils/logger.ts b/src/utils/logger.ts
index c99b3d4..1e90da9 100644
--- a/src/utils/logger.ts
+++ b/src/utils/logger.ts
@@ -4,6 +4,33 @@ import { getAgentDir } from './paths';
 
 export type LogLevel = 'info' | 'warn' | 'error' | 'debug';
 
+/**
+ * Safely stringify an object, handling circular references
+ * This prevents "Converting circular structure to JSON" errors
+ * when logging objects like axios errors that contain socket references
+ */
+function safeStringify(obj: unknown): string {
+  const seen = new WeakSet();
+  return JSON.stringify(obj, (key, value) => {
+    // Handle Error objects specially
+    if (value instanceof Error) {
+      return {
+        name: value.name,
+        message: value.message,
+        stack: value.stack,
+      };
+    }
+    // Handle circular references
+    if (typeof value === 'object' && value !== null) {
+      if (seen.has(value)) {
+        return '[Circular]';
+      }
+      seen.add(value);
+    }
+    return value;
+  });
+}
+
 class Logger {
   private logFilePath: string;
 
@@ -22,7 +49,7 @@ class Logger {
   private formatMessage(level: LogLevel, message: string, ...args: unknown[]): string {
     const timestamp = new Date().toISOString();
     const formattedArgs = args
-      .map((arg) => (typeof arg === 'object' ? JSON.stringify(arg) : String(arg)))
+      .map((arg) => (typeof arg === 'object' ? safeStringify(arg) : String(arg)))
       .join(' ');
     return `[${timestamp}] [${level.toUpperCase()}] ${message} ${formattedArgs}`;
   }