# Downgrade from yocto zeus to thud and state version incompatibilty **URL:** \ **Category:** General Discussions\ **Created:** [April 30, 2020, 2:45pm UTC](https://hub.mender.io/t/downgrade-from-yocto-zeus-to-thud-and-state-version-incompatibilty/1863 "2020-04-30T14:45:25Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![alexandre\_cenareo](https://avatars.discourse-cdn.com/v4/letter/a/47e85d/32.png) [@alexandre\_cenareo](https://hub.mender.io/u/alexandre_cenareo)\ **Post date:** [April 30, 2020, 2:45pm UTC](https://hub.mender.io/t/downgrade-from-yocto-zeus-to-thud-and-state-version-incompatibilty/1863/1 "2020-04-30T14:45:25Z")
Hi, I ran into a problem with mender when trying to downgrade a device from a yocto zeus rootfs (mender client version 2.2.0) to a previous thud rootfs (mender client version 1.7.0). What is observed is that the downgrade is done but after a reboot (the reboot is not initiated by mender), the device goes back to the zeus rootfs. And it gets even worse: it is now impossible to upgrade/downgrade from mender. What happen is: - Once updated to mender 2.2.0, `/data/mender-store` will store states in “version 2” - In case of a downgrade, the mender 1.7.0 client is unable to read state: ```auto mender[226]: time="2020-04-30T16:21:51+02:00" level=error msg="failed to restore state data: unsupported state data version" module=state ``` - So it considers the update as failed, and want to upload status report: ```auto mender[226]: time="2020-04-30T16:21:51+02:00" level=info msg="State transition: init [none] -> update-error [ArtifactFailure]" module=mender mender[226]: time="2020-04-30T16:21:51+02:00" level=info msg="State transition: update-error [ArtifactFailure] -> update-status-report [none]" module=mender ``` - But as it was unable to read the state, it doesn’t know the deployment id so it tries to connect to ` /api/devices/v1/deployments/device/deployments/unknown/status` and got 500 error ```auto mender[226]: time="2020-04-30T16:21:51+02:00" level=error msg="got unexpected HTTP status when reporting status: 500" module="client_status" ``` - As the update is never commited, a reboot makes that the device boots on zeus partition - From there, there is always the state “update-status-report” that tries to send to `/api/devices/v1/deployments/device/deployments/unknown/status`, and mender is “bricked”, as it won’t ever change state. As a workaround, we can delete `/data/mender/store` and it will “unbrick” mender, then downgrade and once downgrade is done, again delete `/data/mender/store`, restart mender and run `mender -commit`. You will understand that this issue is quite serious because: - It prevents mender from downgrading - It “bricks” mender itself I will try to add mender 2.2.0 to my yocto thud image, but I think it should be fixed or at least be clearly specified in the documentation that you can’t go back from a mender client \> 2.0 to a \< 2.0. Or maybe I am missing something ? ---
**Author:** ![kacf](https://yyz2.discourse-cdn.com/flex036/user_avatar/hub.mender.io/kacf/32/146_2.png) [@kacf](https://hub.mender.io/u/kacf)\ **Post date:** [May 4, 2020, 6:47am UTC](https://hub.mender.io/t/downgrade-from-yocto-zeus-to-thud-and-state-version-incompatibilty/1863/2 "2020-05-04T06:47:10Z")
It’s correct, downgrading to 1.7.x from a 2.x.x version is not supported, except when the upgrade from 1.7.x to 2.x.x fails and it has to roll back. In this specific case it is supported. > [@alexandre\_cenareo](#): > > From there, there is always the state “update-status-report” that tries to send to `/api/devices/v1/deployments/device/deployments/unknown/status` , and mender is “bricked”, as it won’t ever change state. Not for that deployment, but if you make a new deployment, will it not be part of it? ---
**Author:** ![alexandre\_cenareo](https://avatars.discourse-cdn.com/v4/letter/a/47e85d/32.png) [@alexandre\_cenareo](https://hub.mender.io/u/alexandre_cenareo)\ **Post date:** [May 4, 2020, 7:17am UTC](https://hub.mender.io/t/downgrade-from-yocto-zeus-to-thud-and-state-version-incompatibilty/1863/3 "2020-05-04T07:17:34Z")
> It’s correct, downgrading to 1.7.x from a 2.x.x version is not supported, except when the upgrade from 1.7.x to 2.x.x fails and it has to roll back. In this specific case it is supported. Well, it’s a bummer, very surprising for an update software and a very important thing to say in documentation ! > Not for that deployment, but if you make a new deployment, will it not be part of it? No, as I said, the mender daemon stays in state `update-status-report` and won’t change. It won’t even update inventory or check for new updates ---
**Author:** ![kacf](https://yyz2.discourse-cdn.com/flex036/user_avatar/hub.mender.io/kacf/32/146_2.png) [@kacf](https://hub.mender.io/u/kacf)\ **Post date:** [May 4, 2020, 9:13am UTC](https://hub.mender.io/t/downgrade-from-yocto-zeus-to-thud-and-state-version-incompatibilty/1863/4 "2020-05-04T09:13:10Z")
> [@alexandre\_cenareo](#): > > Well, it’s a bummer, very surprising for an update software and a very important thing to say in documentation ! You’re right, I have added a note about it [here](https://github.com/mendersoftware/mender-docs/pull/951).