After I change the nus uuid, the smartphone cannot receive data.https://devzone.nordicsemi.com/f/nordic-q-a/65825/after-i-change-the-nus-uuid-the-smartphone-cannot-receive-dataHi, I am using nRF52840 SDK 15.3.0 Keil IDE The soft device is S140 JLinkRTTViewer for debug Question 1) I program based on peripheral\app_uart 1) Connection with nRFConnect is successful Nordic UART service is displayed en-USTelligent Community 13Fri, 11 Sep 2020 12:18:53 GMTRE: After I change the nus uuid, the smartphone cannot receive data.https://devzone.nordicsemi.com/thread/269164?ContentTypeID=1Fri, 11 Sep 2020 12:18:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a04c3764-28fc-4374-a383-af434fc99367Karl Ylvisaker<p>Hello,</p> [quote user=""]is it correct ?[/quote] <p>That depends, did you change the nus UUID of only the TX service?<br />If you change the UUID of only one service, or if you did not change it accordingly in the central, then this will not work. I am guessing that the ble_nus_data_send function fails because the central did not recognize the new uuid and therefore did not enable notifications on the characteristic. When the nRF52840 then went to sent a notification, it will generate an error.<br />Could you please elaborate on exactly where you changed the UUID, and why you made the change?<br /><br />Could you also verify that you have DEBUG defined in your preprocessor defines?<br />It should look like the included image:<br /><img alt=" " src="https://devzone.nordicsemi.com/resized-image/__size/320x240/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-3311dc1f96f54246857898f6b3b46515/enabling_5F00_debug_5F00_SES.PNG" /><br />With DEBUG defined in the preprocessor defines the generated error and which function returned the error will be written to the log.<br /><br />Best regards,<br />Karl</p><div style="clear:both;"></div>