# Troubleshooting

## Windows: OAuth Port Error (EACCES)

On Windows, the default OAuth callback port (51121) may be reserved by Hyper-V, WSL2, or Docker. If you see:

```
Error: listen EACCES: permission denied 0.0.0.0:51121
```

The proxy will automatically try fallback ports (51122-51126). If all ports fail, try these solutions:

### Option 1: Use a Custom Port (Recommended)

Set a custom port outside the reserved range:

```bash
# Windows PowerShell
$env:OAUTH_CALLBACK_PORT = "3456"
antigravity-claude-proxy start

# Windows CMD
set OAUTH_CALLBACK_PORT=3456
antigravity-claude-proxy start

# Or add to your .env file
OAUTH_CALLBACK_PORT=3456
```

### Option 2: Reset Windows NAT

Run as Administrator:

```powershell
net stop winnat
net start winnat
```

### Option 3: Check Reserved Ports

See which ports are reserved:

```powershell
netsh interface ipv4 show excludedportrange protocol=tcp
```

If 51121 is in a reserved range, use Option 1 with a port outside those ranges.

### Option 4: Permanently Exclude Port (Admin)

Reserve the port before Hyper-V claims it (run as Administrator):

```powershell
netsh int ipv4 add excludedportrange protocol=tcp startport=51121 numberofports=1
```

> **Note:** The server automatically tries fallback ports (51122-51126) if the primary port fails.

---

## "Could not extract token from Antigravity"

If using single-account mode with Antigravity:

1. Make sure Antigravity app is installed and running
2. Ensure you're logged in to Antigravity

Or add accounts via OAuth instead: `antigravity-claude-proxy accounts add`

## 401 Authentication Errors

The token might have expired. Try:

```bash
curl -X POST http://localhost:8080/refresh-token
```

Or re-authenticate the account:

```bash
antigravity-claude-proxy accounts
```

## Rate Limiting (429)

With multiple accounts, the proxy automatically switches to the next available account. With a single account, you'll need to wait for the rate limit to reset.

## Account Shows as "Invalid"

Re-authenticate the account:

```bash
antigravity-claude-proxy accounts
# Choose "Re-authenticate" for the invalid account
```