I’m encountering a Null Pointer Exception (NPE) when trying to delete a subscription for a monetized API in WSO2 API Manager 4.4.0. The issue does not occur for non-monetized APIs. The error occurs in the APIConsumerImpl.removeSubscription() method, specifically when trying to invoke tier.getTierPlan() on a null tier object.

Here’s the error I see in the UI: Error occurred when deleting subscription

Request URL: https://linuxmachine:9443/api/am/devportal/v3/subscriptions/7efe7ca0-df76-4ea6-87c8-cea1fb4888c7
Request Method: DELETE
Response: {
    "code": 500,
    "message": "Internal server error",
    "description": "The server encountered an internal error. Please contact administrator.",
    "moreInfo": "",
    "error": []
}

And here’s the relevant error log from the WSO2 server:

[2025-02-20 15:57:30,199] ERROR - GlobalThrowableMapper An unknown exception has been captured by the global exception mapper.
java.lang.NullPointerException: Cannot invoke ".wso2.carbon.apimgt.api.model.Tier.getTierPlan()" because "tier" is null
    at .wso2.carbon.apimgt.impl.APIConsumerImpl.removeSubscription_aroundBody64(APIConsumerImpl.java:1383)
    at .wso2.carbon.apimgt.impl.APIConsumerImpl.removeSubscription(APIConsumerImpl.java:1) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.impl.UserAwareAPIConsumer.removeSubscription_aroundBody6(UserAwareAPIConsumer.java:83) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.impl.UserAwareAPIConsumer.removeSubscription(UserAwareAPIConsumer.java:1) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.impl.APIConsumerImpl.removeSubscription_aroundBody68(APIConsumerImpl.java:1457) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.impl.APIConsumerImpl.removeSubscription(APIConsumerImpl.java:1) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.impl.UserAwareAPIConsumer.removeSubscription_aroundBody8(UserAwareAPIConsumer.java:88) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.impl.UserAwareAPIConsumer.removeSubscription(UserAwareAPIConsumer.java:1) ~[.wso2.carbon.apimgt.impl_9.30.67.jar:?]
    at .wso2.carbon.apimgt.rest.api.store.v1.impl.SubscriptionsApiServiceImpl.subscriptionsSubscriptionIdDelete(SubscriptionsApiServiceImpl.java:534) ~[?:?]
    at .wso2.carbon.apimgt.rest.api.store.v1.SubscriptionsApi.subscriptionsSubscriptionIdDelete(SubscriptionsApi.java:131) ~[?:?]
    ...

1. What I Tried:

• Set up a fresh installation of WSO2 API Manager 4.4.0 on a Linux machine.
• Created a monetized API (enabled monetization for the API).
• Subscribed to the API.
• Attempted to delete the subscription.

2. What I Expected:

• The subscription should be deleted successfully, as it works for non-monetized APIs.

3. What Actually Happened:

• The deletion fails with a 500 Internal Server Error and a Null Pointer Exception in the logs.

Additional Information

Environment:

• WSO2 API Manager Version: 4.4.0
• Operating System: Linux
• Database: Oracle (fresh installation)
• Deployment: Docker container