https://devzone.nordicsemi.com/f/nordic-q-a/15946/stdbool-h-is-missing-where-is-itI tried to build the example project &quot;ble_app_uart&quot; bundled with nRF5 SDK (nRF5_SDK_11.0.0_89a8197) within the MDK-Lite V5.18K. It failed and I got the following messages: *** Using Compiler &#39;V5.06 update 1 (build 61)&#39;, folder: &#39;C:\Keil_v5\ARM\ARMCCen-USTelligent Community 13Thu, 25 Aug 2016 11:10:40 GMThttps://devzone.nordicsemi.com/thread/60834?ContentTypeID=1Thu, 25 Aug 2016 11:10:40 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f07b9004-2757-4c55-9840-662a2f7a6b17Susheel Nuguru<p>it should come with KEIL intallation, if it is missing then something went wrong. It should be located in KEIL_DIR\ARM\ARMCC\include</p><div style="clear:both;"></div>