Context sources support read methods only, such as get_customer or get_value{...}. Methods that change data or application state (for example, setters, save, load, delete, add, remove, or reset methods) and methods that return database resources, connections, or collections are not supported. Subscriptions created in the Admin or with the REST API that use an unsupported method are rejected. For existing subscriptions, an unsupported context value resolves to null and the reason is logged.

PaaS Only To adjust the list of unsupported methods, add or override entries in the deniedMethods or deniedPatterns arguments of Magento\AdobeCommerceOutOfProcessExtensibility\Model\Context\MethodAccessValidator in the etc/di.xml file of a custom module.