When Debug Mode is enabled, Graph API response may contain additional fields that explain potential issues with the request.
To enable debug mode, use the debug
query string parameter. For example:
curl -i -X GET \
"https://graph.facebook.com/{user-id}
?fields=friends
&debug=all
&access_token={your-access-token}"
If user_friends
permission was not granted, this produces the following response:
{ "data": [ ], "__debug__": { "messages": [ { "message": "Field friends is only accessible on User object, if user_friends permission is granted by the user", "type": "warning" }, { "link": "https://developers.facebook.com/docs/apps/changelog#v2_0", "message": "Only friends who have installed the app are returned in versions greater or equal to v2.0.", "type": "info" } ] } }
The debug
parameter value can be set to "all" or to a minimal requested severity level that corresponds to type
of the message:
Debug Param Value | What Will Be Returned |
---|---|
all | All available debug messages. |
info | Debug messages with type info and warning. |
warning | Only debug messages with type warning. |
Debug information, when available, is returned as a JSON object under the __debug__
key in the messages
array. Every element of this array is a JSON object that contains the following fields:
Field | Datatype | Description |
---|---|---|
message | String | The message. |
type | String | The message severity. |
link | String | [Optional] A URL pointing to related information. |
You can also use Debug Mode with Graph API Explorer.
When you're building an app and making Graph API requests, you might find it useful to determine what API version you're getting a response from. For example, if you're making calls without a version specified, the API version that responds may not be known to you.
The Graph API supplies a request header with any response called facebook-api-version
that indicates the exact version of the API that generated the response. For example, a Graph API call that generates a request with v2.0 produces the following HTTP header:
facebook-api-version:v2.0
This facebook-api-version
header allows you to determine whether API calls are being returned from the version that you expect.
When reporting a bug in the Graph API, we include some additional request headers to send with your bug report to help us pinpoint and reproduce your issue. These request headers are X-FB-Debug
, x-fb-rev
, and X-FB-Trace-ID
.