# Common problems

Discover the possible causes and solutions for common issues.

This page catalogs the common errors returned across all API services, including authentication, request validation, and server errors.

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Use the summary below to quickly jump to a specific topic:

- [Authorization required](/reference/api/error/authorization-required): Resolve authorization required errors.
- [Missing client ID](/reference/api/error/missing-client-id): Resolve missing client ID errors.
- [Invalid client ID](/reference/api/error/invalid-client-id): Resolve invalid client ID errors.
- [Missing application ID](/reference/api/error/missing-application-id): Resolve missing application ID errors.
- [Invalid application ID](/reference/api/error/invalid-application-id): Resolve invalid application ID errors.
- [Unknown application ID](/reference/api/error/unknown-application-id): Resolve unknown application ID errors.
- [Missing API key](/reference/api/error/missing-api-key): Resolve missing API key errors.
- [Invalid API key](/reference/api/error/invalid-api-key): Resolve invalid API key errors.
- [Unknown API key](/reference/api/error/unknown-api-key): Resolve unknown API key errors.
- [Invalid token](/reference/api/error/invalid-token): Resolve invalid token errors.
- [Expired token](/reference/api/error/expired-token): Resolve expired token errors.
- [Unsigned token](/reference/api/error/unsigned-token): Resolve unsigned token errors.
- [Forbidden origin](/reference/api/error/forbidden-origin): Resolve forbidden origin errors.
- [Insufficient permission](/reference/api/error/insufficient-permission): Resolve insufficient permission errors.
- [Quota exceeded](/reference/api/error/quota-exceeded): Resolve quota exceeded errors.
- [Past due subscription](/reference/api/error/past-due-subscription): Resolve past due subscription errors.
- [Invalid method](/reference/api/error/invalid-method): Resolve invalid method errors.
- [Tracking and personalization suspended](/reference/api/error/tracking-and-personalization-suspended): Resolve tracking and personalization suspended errors.
- [Invalid input](/reference/api/error/invalid-input): Resolve request validation errors.
- [Invalid payload](/reference/api/error/invalid-payload): Resolve invalid payload errors.
- [Resource not found](/reference/api/error/resource-not-found): Resolve resource not found errors.
- [Internal error](/reference/api/error/internal-error): Resolve internal server errors.