Apollo Common Errors

Overview

Comprehensive guide to diagnosing and fixing Apollo.io API errors. Apollo uses x-api-key header authentication and the base URL https://api.apollo.io/api/v1/. Apollo distinguishes between master and standard API keys — many endpoints require master keys.

Prerequisites

Valid Apollo.io API credentials
Node.js 18+ or Python 3.10+

Instructions

Step 1: Identify the Error Category

// src/apollo/error-handler.ts
import { AxiosError } from 'axios';

type ErrorCategory = 'auth' | 'permission' | 'rate_limit' | 'validation' | 'server' | 'network';

function categorizeError(err: AxiosError): ErrorCategory {
  if (!err.response) return 'network';
  switch (err.response.status) {
    case 401: return 'auth';
    case 403: return 'permission';
    case 429: return 'rate_limit';
    case 400: case 422: return 'validation';
    default: return err.response.status >= 500 ? 'server' : 'validation';
  }
}

Step 2: Handle 401 — Invalid API Key

// Most common cause: missing x-api-key header or wrong key format
async function diagnoseAuth() {
  try {
    const response = await fetch('https://api.apollo.io/api/v1/auth/health', {
      headers: { 'x-api-key': process.env.APOLLO_API_KEY! },
    });
    const data = await response.json();
    if (data.is_logged_in) {
      console.log('API key is valid');
    } else {
      console.error('API key is invalid or expired');
      console.error('  Generate a new one at: Apollo > Settings > Integrations > API Keys');
    }
  } catch (err: any) {
    console.error('Cannot reach Apollo API:', err.message);
  }
}

Common 401 causes:

Using api_key query parameter instead of x-api-key header
Key was revoked or regenerated in the dashboard
Key has trailing whitespace (check with echo -n "$APOLLO_API_KEY" | wc -c)

Step 3: Handle 403 — Wrong Key Type

Standard API key: search + enrichment only
Master API key:   full access (contacts, sequences, deals, tasks)

Endpoints that require a master key:

POST /contacts (create/update)
POST /emailer_campaigns/search (sequences)
POST /emailer_campaigns/{id}/add_contact_ids
POST /opportunities (deals)
POST /tasks (tasks)
DELETE /contacts/{id}

// Diagnose: test a master-key-only endpoint
async function diagnoseMasterKey() {
  try {
    await client.post('/contacts/search', { per_page: 1 });
    console.log('Master API key confirmed');
  } catch (err: any) {
    if (err.response?.status === 403) {
      console.error('Your API key is a standard key. Master key required.');
      console.error('  Go to Apollo > Settings > Integrations > API Keys');
      console.error('  Generate a new key with "Master Key" type');
    }
  }
}

Step 4: Handle 429 — Rate Limiting

Apollo uses fixed-window rate limiting per endpoint category:

Endpoint Category         | Limit      | Window  | Burst
--------------------------+------------+---------+------
People Search             | 100/min    | 1 min   | 10/sec
People Enrichment         | 100/min    | 1 min   | 10/sec
Bulk People Enrichment    | 10/min     | 1 min   | 2/sec
Organization Enrichment   | 100/min    | 1 min   | 10/sec
Contacts (CRUD)           | 100/min    | 1 min   | 10/sec
Sequences                 | 100/min    | 1 min   | 10/sec

// Respect Retry-After header
async function handleRateLimit<T>(fn: () => Promise<T>): Promise<T> {
  try {
    return await fn();
  } catch (err: any) {
    if (err.response?.status === 429) {
      const retryAfter = parseInt(err.response.headers['retry-after'] ?? '60', 10);
      console.warn(`Rate limited. Waiting ${retryAfter}s...`);
      await new Promise((r) => setTimeout(r, retryAfter * 1000));
      return fn();
    }
    throw err;
  }
}

Step 5: Handle 422 — Validation Errors

// Common 422 causes:
//   - per_page > 100 on search endpoints
//   - Missing required fields on /contacts POST (first_name, last_name)
//   - Invalid email format on /people/match
//   - page > 500 on /mixed_people/api_search (50,000 record limit)

function logValidationError(err: AxiosError) {
  const body = err.response?.data as any;
  console.error('Validation error:', {
    status: err.response?.status,
    message: body?.message ?? body?.error,
    errors: body?.errors,
    url: err.config?.url,
    body: typeof err.config?.data === 'string' ? JSON.parse(err.config.data) : err.config?.data,
  });
}

Step 6: Build Comprehensive Error Middleware

// src/apollo/error-middleware.ts
import { AxiosError, AxiosInstance } from 'axios';

export function attachErrorHandler(client: AxiosInstance) {
  client.interceptors.response.use(
    (response) => response,
    (err: AxiosError) => {
      const status = err.response?.status;
      const body = err.response?.data as any;
      const endpoint = err.config?.url ?? 'unknown';

      const info = {
        status,
        endpoint,
        message: body?.message ?? err.message,
        timestamp: new Date().toISOString(),
      };

      switch (categorizeError(err)) {
        case 'auth':
          console.error('[APOLLO AUTH] Invalid x-api-key header', info);
          break;
        case 'permission':
          console.error('[APOLLO PERMISSION] Master key required for this endpoint', info);
          break;
        case 'rate_limit':
          console.warn('[APOLLO RATE LIMIT]', info);
          break;
        case 'validation':
          console.error('[APOLLO VALIDATION]', info);
          break;
        case 'server':
          console.error('[APOLLO SERVER] Check status.apollo.io', info);
          break;
        case 'network':
          console.error('[APOLLO NETWORK] Cannot reach api.apollo.io', info);
          break;
      }

      return Promise.reject(err);
    },
  );
}

Error Reference

Code	Meaning	Fix
401	Invalid or missing `x-api-key` header	Verify key in dashboard, check header name
403	Standard key used for master-only endpoint	Generate master API key
422	Bad request body	Check field names, per_page <= 100, page <= 500
429	Rate limit exceeded	Read `Retry-After` header, implement backoff
500	Apollo server error	Retry with backoff, check status.apollo.io
ECONNREFUSED	Network/firewall	Allow outbound HTTPS to `api.apollo.io:443`

Examples

Quick cURL Diagnostic

# Test auth (should return is_logged_in: true)
curl -s -H "x-api-key: $APOLLO_API_KEY" \
  https://api.apollo.io/api/v1/auth/health | python3 -m json.tool

# Test master key (returns contacts or 403)
curl -s -X POST -H "Content-Type: application/json" -H "x-api-key: $APOLLO_API_KEY" \
  -d '{"per_page":1}' https://api.apollo.io/api/v1/contacts/search | python3 -m json.tool

Resources

Next Steps

Proceed to apollo-debug-bundle for collecting debug evidence.

apollo-common-errors