# Error codes | Error code | Error message | Description | | ---------- | ------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------ | | 402 | Sender /Receiver is already running. HINT: Stop sender to start playing again. | This error is seen when the user tries to start the SDK receiver or sender method more than one time. | | 403 | SDK Not Initialised | The SDK Throws this error when SDK methods are being used without initialising SDK Object. Please make sure SDK objects are initialised properly before use. | | 404 | Missing Permission | This error is received when the user tries to initialise SDK without required permissions. | | 501 | Invalid SDK Key | Wrong SDK Key passed while creating TrillSDK object. | | 410 | Already Playing | This error comes when SDK is playing and user tries to play without stopping the current playing event. | | 411 | Not Playing | This error is seen when SDK is not playing and user tries to stop playing. | | 412 | Already Recording | This error is seen when SDK is receiving and user tries to receive without stopping the current receiving event. | | 413 | Not Recording | This error is seen when SDK is not receiving and the user tried to stop receiving. | | 414 | Cannot send while receiving | This error is seen when SDK is in receiving mode and user tries to play something. | | 415 | Cannot receive while sending | This error is seen when SDK is in playing mode and user tries to call receiver methods. | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://trillbit.gitbook.io/trillbit-sdk/android-support/trill-sdk-for-android/troubleshooting/error-codes.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.