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When errors/exceptions occur in the system, the API Manager throws XML-based error responses to the client by default. To change the format of these error responses, you change the relevant XML file in the <AM_HOME>/repository/deployment/server/synapse-configs/default/sequences directory. The directory includes multiple XML files, named after the type of errors that occur. You must select the correct file.

For example, to change the message type of authorization errors, open the <APIM_HOME>/repository/deployment/server/synapse-configs/default/sequences/_auth_failure_handler.xml file and change  application/xml to something like  application/json .

<sequence name="_auth_failure_handler_" xmlns="http://ws.apache.org/ns/synapse">
 <property name="error_message_type" value="application/json"/>
 <sequence key="_cors_request_handler_"/>
</sequence>

Similarly, to change the error messages of throttling errors (e.g., quota exceeding), change the _throttle_out_handler_.xml file; resource mismatch errors, the _resource_mismatch_handler_.xml file, etc.

Given below are some error codes and their meanings.

API handlers error codes

Error codeError MessageDescriptionExample
700700
API blockedThis API has been blocked temporarily. Please try again later or contact the system administrators.Invoke an API which is in the BLOCKED lifecycle state
900800
Message throttled out

The maximum number of requests that can be made to the API within a designated time period is reached and the API is throttled for the user.

Invoke an API exceeding the tier limit
900801
Hard limit exceededHard throttle limit has been reachedInvoke an API exceeding the hard throttle limit
900900

Unclassified authentication failure

An unspecified error has occurredBackend service for key validation is not accessible when trying to invoke an API
900901

Invalid credentials

Invalid authentication information providedUsing an older access token after an access token has been renewed.
900902

Missing credentials

No authentication information providedAccessing an API without Authorization: Bearer header
900905

Incorrect access token type is provided

The access token type used is not supported when invoking the API. The supported access token types are application and user accesses tokens. See Access Tokens.

Invoke an API with application token, where the resource only allows application user tokens
900906

No matching resource found in the API for the given request

A resource with the name in the request can not be found in the API.Invoke an API resource that is not available
900907

The requested API is temporarily blocked

Happens when the API user is blocked.Invoke API resource with a subscription that has been blocked by the API publisher
900908

Resource forbidden

The user invoking the API has not been granted access to the required resource.Invoke an unsubscribed API
900909

The subscription to the API is inactive

The status of the API has changed to an inaccessible/unavailable state. Invoke an API resource with a subscription that has not yet been approved by the administrator.
900910

The access token does not allow you to access the requested resource

Can not access the required resource with the provided access token. Check the valid resources that can be accessed with this token.

Invoke API resource with an access token that is not generated to be used with the resource's scope.
102511Incomplete payloadThe payload sent with the request is too large and the client is unable to keep the connection alive until the payload is completely transferred to the API GatewaySending a large PDF file with the POST request

The error codes 900903 (Access token expired) and 900904 (Access token inactive) are deprecated from API Manager 1.9.0 onwards. Alternatively, error code 900901 will be sent when the token is invalid or inactive.

Sequences error codes

Error codeDescription
900901
Production/sandbox key offered to the API with no production/sandbox endpoint
400
Server cannot process the request due to an error in the request sent by the client
403
No matching resource found in the API for the given request

In addition to the above error codes, we have engaged Synapse-level error codes to the default fault sequence and fault sequences of the API Manager. For information, see Error Handling in WSO2 ESB documentation.


Custom error messages

To send a custom message with a custom HTTP status code, you execute an additional sequence that can generate a new error message. You then override the message body, HTTP status code and other values.

The following steps demonstrate how to override a throttled-out message's HTTP status code as a custom error message:

  1. Go to <APIM_HOME> /repository/deployment/server/synapse-configs/default/sequences directory and create the file convert.xml as follows.

    <sequence xmlns="http://ws.apache.org/ns/synapse" name="convert">
        <payloadFactory media-type="xml">
            <format>
                <am:fault xmlns:am="http://wso2.org/apimanager">
                    <am:code>$1</am:code>
                    <am:type>Status report</am:type>
                    <am:message>Runtime Error</am:message>
                    <am:description>$2</am:description>
                </am:fault>
            </format>
            <args>
                <arg evaluator="xml" expression="$ctx:ERROR_CODE"/>
                <arg evaluator="xml" expression="$ctx:ERROR_MESSAGE"/>
            </args>
        </payloadFactory>
        <property name="RESPONSE" value="true"/>
        <header name="To" action="remove"/>
        <property name="HTTP_SC" value="555" scope="axis2"/>
        <property name="NO_ENTITY_BODY" scope="axis2" action="remove"/>
        <property name="ContentType" scope="axis2" action="remove"/>
        <property name="Authorization" scope="transport" action="remove"/>
        <property name="Access-Control-Allow-Origin" value="*" scope="transport"/>
        <property name="Host" scope="transport" action="remove"/>
        <property name="Accept" scope="transport" action="remove"/>
        <property name="X-JWT-Assertion" scope="transport" action="remove"/>
        <property name="messageType" value="application/json" scope="axis2"/>
        <send/>
    </sequence>

    Alternatively, you can use the Source View of the APIm Management Console as follows to edit the synapse configuration:

    • Start the API Manager and log in to the Management Console. (https://<Server Host>:9443/carbon).
    • Go to Manager -> Source View.
    • Copy the content of the sequence in convert.xml, paste it as a new sequence in the source view and update it.
  2. Check the logs to see whether there are issues in the deployment.  If the deployment is successful, you see a message like the following in the system logs:

    [2015-04-13 09:17:38,885]  INFO - SequenceDeployer Sequence named 'convert' has been deployed from file : <APIM_HOME>/repository/deployment/server/synapse-configs/default/sequences/convert.xml
  3. Invoke the API until the throttling limit exceeds and the new requests get throttled out. 

    curl -v -H "Authorization: Bearer <Access_Token>" http://localhost:8280/<API_name>/<context>/<version>
  4. Note that you get following response:

    * About to connect() to 127.0.0.1 port 8280 (#0)
    *   Trying 127.0.0.1...
    * Adding handle: conn: 0x17a2db0
    * Adding handle: send: 0
    * Adding handle: recv: 0
    * Curl_addHandleToPipeline: length: 1
    * - Conn 0 (0x17a2db0) send_pipe: 1, recv_pipe: 0
    * Connected to 127.0.0.1 (127.0.0.1) port 8280 (#0)
    > GET /testam/sanjeewa/1.0.0 HTTP/1.1
    > User-Agent: curl/7.32.0
    > Host: 127.0.0.1:8280
    > Accept: */*
    > Authorization: Bearer 7f855a7d70aed820a78367c362385c86
    > 
    < HTTP/1.1 555 
    < Access-Control-Allow-Origin: *
    < Content-Type: application/json
    < Date: Mon, 13 Apr 2015 05:30:12 GMT
    * Server WSO2-PassThrough-HTTP is not blacklisted
    < Server: WSO2-PassThrough-HTTP
    < Transfer-Encoding: chunked
    < 
    * Connection #0 to host 127.0.0.1 left intact
    {"fault":{"code":"900800","type":"Status report","message":"Runtime Error","description":"Message throttled out"}}

WSO2 API Manager has the following default fault sequences located in <APIM_HOME> /repository/deployment/server/synapse-configs/default/sequences directory.

Fault SequenceDescription
fault.xml

This is the primary fault sequence that gets invoked when an error occurs during the execution of an API resources

main.xmlThis sequence is called when the endpoint being called does not exist
auth_failure_handler.xmlThis sequence is called when an API authentication error is encountered
production_key_error.xmlThis sequence is called when a Production key is used to invoke an API that does not have a Production endpoint defined
sandbox_key_error.xmlThis sequence is called when a Sandbox key is used to invoke an API that does not have a Sandbox endpoint defined
throttle_out_handler.xmlThis sequence is called when a given request to an API gets throttled out
token_fault.xmlThis sequence is called when there is an error in invoking the token API
resource_mismatch_handler.xmlThis sequence is called when a matching resource cannot be found by the gateway to the corresponding resource being invoked

The default sequences can also be customized as shown in the section above.

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