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This issue has nothing to do with whether the player is an anonymous user. Anonymous users have the same access rights to PlayFab APIs as other non-anonymous users. The Unauthorized error “This API method does not allow anonymous callers” indicates you don’t provide the entity token/session ticket which required to call this API. In your case, calling the API ExecuteInventoryOperations in the Azure Function needs title entity token to perform authentication. In fact, no matter the method for executing a script the Title Authentication context is always provided, and it includes the Title ID and Title Entity Token used to execute the script. You can refer to https://learn.microsoft.com/en-us/gaming/playfab/features/automation/cloudscript-af/cloudscript-af-context#use-the-shared-title-authentication-context-model for more details. In addition, if you mean that this unauthorized error occurs when the player calls the API ExecuteFunction, since this API also requires an Entity Token (players can obtain it after successfully logging in), you may check if the EntityToken is successfully passed.