kitten.sh
1---
2title: Errors
3order: 5
4---
5
6# Error handling
7
8When we use a GraphQL API there are two kinds of errors we may encounter: Network Errors and GraphQL
9Errors from the API. Since it's common to encounter either of them, there's a
10[`CombinedError`](../api/core.md#combinederror) class that can hold and abstract either.
11
12We may encounter a `CombinedError` when using `urql` wherever an `error` may be returned, typically
13in results from the API. The `CombinedError` can have one of two properties that describe what went
14wrong.
15
16- The `networkError` property will contain any error that stopped `urql` from making a network
17 request.
18- The `graphQLErrors` property may be an array that contains [normalized `GraphQLError`s as they
19 were received in the `errors` array from a GraphQL API.](https://graphql.org/graphql-js/error/)
20
21Additionally, the `message` of the error will be generated and combined from the errors for
22debugging purposes.
23
24
25
26It's worth noting that an `error` can coexist and be returned in a successful request alongside
27`data`. This is because in GraphQL a query can have partially failed but still contain some data.
28In that case `CombinedError` will be passed to us with `graphQLErrors`, while `data` may still be
29set.