https://test-devzone.nordicsemi.com/f/nordic-q-a/88181/null-doesn-t-match-connHello community! I know this sounds almost impossible... but it&#39;s happening I&#39;m debugging an application based on peripheral_uart. When I call bt_nus_send(NULL, buf-&gt;data, buf-&gt;len); if I debug this sentence in bluetooth\services\nusen-USTelligent Community 13 Non-ProductionTue, 07 Jun 2022 05:38:24 GMThttps://test-devzone.nordicsemi.com/thread/371015?ContentTypeID=1Tue, 07 Jun 2022 05:38:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:1ecb16e5-399e-4cde-ae5e-6e9484fcbfd0user107544<p>Hi Einar:</p> <p></p> <p>Sorry for my late reply. It&#39;s probably as you say, a problem on debug optimizations, although I&#39;m not sure 100% Anyway I don&#39;t have this problem anymore.</p> <p>Thank you,</p> <p>David.</p><div style="clear:both;"></div>https://test-devzone.nordicsemi.com/thread/369002?ContentTypeID=1Mon, 23 May 2022 11:50:22 GMT137ad170-7792-4731-bb38-c0d22fbe4515:097a42eb-dde7-4cb2-a38b-a9958904c20fuser7377<p>Hi David,</p> <p>You write that you see this when debugging. Could it be simply that you have built your application with optimization and is stepping or similar? In that case the machine code will not match the C code, and things will look strange. If so, I suggest enabling debug optimization (<code>CONFIG_DEBUG_OPTIMIZATIONS=y</code>). If that is not the issue, then&nbsp;it would be interesting if you could share a project and instructions on how to reproduce so that I can have a look on my end.</p> <p>Einar</p><div style="clear:both;"></div>