https://devzone.nordicsemi.com/f/nordic-q-a/78580/understanding-error-messageHello, Sorry for the basic question, but I am trying to customize an application basing on the ble_app_cgms example. In the debugger terminal on SES I am receiving the following message when I try to access a ble characteristic: &lt;error&gt; nrf_ble_gqen-USTelligent Community 13Mon, 16 Aug 2021 12:00:01 GMThttps://devzone.nordicsemi.com/thread/325104?ContentTypeID=1Mon, 16 Aug 2021 12:00:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2955f564-21e7-4dfc-b80a-649db7f7ae92Jared<p>Hi,<br /><br /></p> <p>Error code 0x08 is&nbsp;NRF_ERROR_INVALID_STATE which is usually returned when you call a function when in an improper&nbsp;state, such as trying to call the advertising function when the device is already advertising. The error message is printed in&nbsp;request_err_code_handle() which again is called from different places in the nrf_ble_gq library. Try using the debugger and check the call stack when the error happens. It will reveal what function that is calling request_err_code_handle() and why.</p> <div> <div><span></span></div> <div><span>regards</span></div> <div><span>Jared</span></div> </div><div style="clear:both;"></div>