All errors from Screen Answerer return JSON responses with this structure:
{
"error": "Error type",
"message": "Detailed error description"
}
HTTP status codes
Screen Answerer uses standard HTTP status codes to indicate success or failure:
| Status | Meaning | Description |
|---|
200 | Success | Request processed successfully |
400 | Bad Request | Missing or invalid request parameters |
401 | Unauthorized | Invalid or rejected API key |
429 | Too Many Requests | Rate limit exceeded |
500 | Internal Server Error | Server or API processing error |
Common errors
400 Bad Request
Missing API key
{
"error": "API key is required"
}
No question or image
{
"error": "No question or image provided"
}
{
"error": "Invalid API key format",
"message": "Please provide a valid Gemini API key"
}
AIza[0-9A-Za-z_-]{35} (server.js:402-406).
curl -X POST http://localhost:3000/process_question_with_key \
-F "apiKey=invalid_key" \
-F "question=What is 2+2?"
401 Unauthorized
API key authentication failure
{
"error": "API key error",
"message": "Invalid API key provided. Please check your API key and try again."
}
429 Too Many Requests
Rate limit exceeded
{
"error": "Rate limit exceeded",
"message": "Please wait before sending another request"
}
Rate limit: 1 request per 5 seconds per client IP (server.js:87)
API quota exceeded
{
"error": "API quota exceeded",
"message": "API quota limit reached. Please try again later."
}
The server implements a global quota limit of 50 API calls per minute to prevent quota exhaustion (server.js:106)
500 Internal Server Error
General processing failure
{
"error": "Failed to process question",
"message": "Detailed error message from Gemini API"
}
Screen monitoring failure
{
"error": "Failed to process screen capture",
"message": "Detailed error message"
}
Retry logic
Screen Answerer implements automatic retry logic with exponential backoff for transient failures.
Retry configuration
- Max retries: 3 attempts (server.js:88)
- Initial delay: 1000ms (server.js:89)
- Backoff strategy: Exponential with jitter (server.js:166)
- Max delay: 10000ms (10 seconds)
Retryable errors
The following errors trigger automatic retries:
- HTTP 429 (rate limit)
- Quota exhaustion messages
- “Resource has been exhausted” errors
// Screen Answerer automatically retries these errors
const retryableErrors = [
'429',
'quota',
'Resource has been exhausted'
];
// Exponential backoff formula (server.js:166)
delay = Math.min(delay * 2, 10000) * (0.8 + Math.random() * 0.4);
Client-side retry example
For errors that aren’t automatically retried, implement your own retry logic:
async function processQuestionWithRetry(question, apiKey, maxRetries = 3) {
let lastError;
for (let attempt = 0; attempt < maxRetries; attempt++) {
try {
const response = await fetch('http://localhost:3000/process_question', {
method: 'POST',
headers: {
'X-API-Key': apiKey,
'Content-Type': 'application/json'
},
body: JSON.stringify({ question })
});
if (response.ok) {
return await response.json();
}
// Don't retry client errors (4xx) except 429
if (response.status >= 400 && response.status < 500 && response.status !== 429) {
throw new Error(await response.text());
}
lastError = await response.json();
// Wait before retrying
const delay = Math.min(1000 * Math.pow(2, attempt), 10000);
await new Promise(resolve => setTimeout(resolve, delay));
} catch (error) {
lastError = error;
if (attempt === maxRetries - 1) throw error;
}
}
throw lastError;
}
Best practices
Handle errors gracefully
- Check HTTP status codes before parsing responses
- Implement exponential backoff for 429 and 500 errors
- Log errors for debugging
- Don’t retry 4xx errors (except 429)
Quota managementMonitor your Google Gemini API quota to avoid hitting limits. The server enforces 50 calls per minute internally.