https://devzone.nordicsemi.com/f/nordic-q-a/1026/problem-with-writing-value-to-gatt-attribute-in-connectionHi. I have a problem with writing value to gatts attribute when device is in connection mode. In my application I want to check if the parameter writing by the client to server&#39;s attribute has a proper value and if not, I want to set there my own valueen-USTelligent Community 13Thu, 28 Nov 2013 16:36:48 GMThttps://devzone.nordicsemi.com/thread/4854?ContentTypeID=1Thu, 28 Nov 2013 16:36:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:11ec34b5-202c-488d-89aa-8902051484f3Ole Morten<p>In this case, I&#39;d suggest that you instead use the Write Command property, and authorization. In that way, you can simply deny the write in the first place. Take a look at <a href="https://devzone.nordicsemi.com/documentation/nrf51/4.4.2/html/group___b_l_e___g_a_t_t_s___w_r_i_t_e___r_e_q___a_u_t_h___m_s_c.html">this MSC</a> to show the sequence of events this would cause. You get this behavior by enabling the wr_auth field when adding the characteristic.</p> <p>If you absolutely don&#39;t want to do this, could you please include what error code you get back from sd_ble_gatts_value_set()?</p><div style="clear:both;"></div>