# PX4 main definitions loss

**URL:** <https://discuss.px4.io/t/px4-main-definitions-loss/32981>\
**Category:** PX4 Autopilot\
**Created:** [June 29, 2023, 1:58pm UTC](https://discuss.px4.io/t/px4-main-definitions-loss/32981 "2023-06-29T13:58:07Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![BlackMatter](https://discuss.px4.io/letter_avatar_proxy/v4/letter/b/ecae2f/32.png) [@BlackMatter](https://discuss.px4.io/u/BlackMatter)\
**Post date:** [June 29, 2023, 1:58pm UTC](https://discuss.px4.io/t/px4-main-definitions-loss/32981/1 "2023-06-29T13:58:07Z")

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Hi everyone,

I’m using PX4 version 1.13.4 with cube orange.  
After startup I happen to find my drone inoperable, doesn’t arm, and therefore doesn’t fly.  
After connecting to QGround I find all definitions lost, including airframe, sensor calibration, magnetometer as can be seen in the following picture.

 ![Image](https://discuss.px4.io/uploads/default/original/2X/6/6ca426b0ebf37ff87645b0a284693fc45181a174.jpeg)  
Does anyone know what can cause this reset to happen?  
It looks like the firmware version remained OK but everything else needed calibration.

Thank you.

PS: I am using customized airframe that is selected from the known list by a parameter. After loading the parameters everything is OK part of the sensors tab.