https://devzone.nordicsemi.com/f/nordic-q-a/10883/sdk-10-0-crashes-my-projectI had a PWM question ( here ). It was recommended that I install SDK 10 and use the PWM files from SDK 10. I installed and copied the PWM files from 10 to 9 and opened my project. Keil opened this pop up: I made the mistake to of clicking updateen-USTelligent Community 13Wed, 16 Dec 2015 09:54:54 GMThttps://devzone.nordicsemi.com/thread/40704?ContentTypeID=1Wed, 16 Dec 2015 09:54:54 GMT137ad170-7792-4731-bb38-c0d22fbe4515:045ddc48-4966-4d3a-bc37-b72382bd58d3Ole Bauck<p>Don&#39;t know if this will solve your problem, but:</p> <p>First go into &quot;Select Software Packs...&quot; and enable the version 3.0.1 (equivalent to SDK 9) for nRF libraries and drivers by ticking the checkboxes.</p> <p><img src="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/03213.Capture.PNG" alt="image description" /></p> <p>Then you can right click on the file in the project window (f.ex. app_error.c), click &quot;option for component class...&quot; and choose to use version 3.0.1.</p> <p><img src="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/5140.Untitled.png" alt="image description" /></p><div style="clear:both;"></div>