https://devzone.nordicsemi.com/f/nordic-q-a/129420/uart-regressions-between-sdk-2-8-0---3-3-0Hi! We have recently upgraded nRF Connect SDK. Since this change, some of our users experience issues with uart - two nRF52840 communicating together. We have not been able to reproduce the issue and the users aren&#39;t very responsive, so we unfortunatelyen-USTelligent Community 13Fri, 16 Oct 2026 14:10:46 GMThttps://devzone.nordicsemi.com/thread/572320?ContentTypeID=1Fri, 16 Oct 2026 14:10:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5ac2451d-0ec4-4eb6-a8b6-25a5b796b3cdkat829<p>Hi Hung!<br /><br />&gt;&nbsp;Since it&#39;s not reproducible on your desk it&#39;s really hard to tell what could be wrong.<br /><br />I know!&nbsp;<span class="emoticon" data-url="https://devzone.nordicsemi.com/cfs-file/__key/system/emoji/1f61e.svg" title="Disappointed">&#x1f61e;</span><br /><br />&gt;&nbsp;Can you reproduce this ? What the fix was ?&nbsp;<br /><br />Yes, with our custom board though. Didn&#39;t try to reduce it to devkits.<br /><br />Well, more of a workaround. We detect garbage and restart the rx on 3rd such failed chunk in a row.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/572318?ContentTypeID=1Fri, 16 Oct 2026 13:54:47 GMT137ad170-7792-4731-bb38-c0d22fbe4515:26fede52-ccd4-4aba-afa8-682f9835f638Hung Bui<p>Hi Karel,&nbsp;<br />Since it&#39;s not reproducible on your desk it&#39;s really hard to tell what could be wrong.<br />The customer need to provide logic analyzer trace on the UART lines.&nbsp;</p> <p></p> [quote user=""]- Limited version of similar problem can be reproduced by a simultaneous cold start of both boards. In that case, one nRF52840&#39;s UARTE async receiver delivers a wrong first byte after every idle gap on the line, with no error event, until RX is disabled and re-enabled once. Fixing this doesn&#39;t make the above issue go away though.[/quote] <p>Can you reproduce this ? What the fix was ?&nbsp;</p><div style="clear:both;"></div>