# Error during delta update

**URL:** <https://hub.mender.io/t/error-during-delta-update/4038>\
**Category:** General Discussions\
**Created:** [August 27, 2021, 12:39pm UTC](https://hub.mender.io/t/error-during-delta-update/4038 "2021-08-27T12:39:06Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![abhishek](https://avatars.discourse-cdn.com/v4/letter/a/7ba0ec/32.png) [@abhishek](https://hub.mender.io/u/abhishek)\
**Post date:** [September 5, 2021, 2:30pm UTC](https://hub.mender.io/t/error-during-delta-update/4038/21 "2021-09-05T14:30:37Z")

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Any update on this? I have used dunfell branch? Shall I change the branch to something latest and repeat the process with the same local and bblayer files?

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**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:** [September 6, 2021, 8:55am UTC](https://hub.mender.io/t/error-during-delta-update/4038/22 "2021-09-06T08:55:08Z")

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Does it help if you put `ENABLE_UART="1"` in `local.conf`? We’ve had reports that this is necessary on recent versions of U-Boot, and this solves the problem for me after trying your config.

Some discussions about this [here](https://hub.mender.io/t/unable-to-boot-raspberry-pi-4-using-offical-image/3672/4) and [here](https://hub.mender.io/t/raspberry-pi-4-model-b/889/33).

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**Author:** ![abhishek](https://avatars.discourse-cdn.com/v4/letter/a/7ba0ec/32.png) [@abhishek](https://hub.mender.io/u/abhishek)\
**Post date:** [October 8, 2021, 11:42am UTC](https://hub.mender.io/t/error-during-delta-update/4038/23 "2021-10-08T11:42:04Z")

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Hi @kacf  
As per suggestion, now I am able to boot in pi4 using root successfully.  
But now, mender client available in Rpi4 does not appear in hosted mender server. Also, I could not do mender setup in Rpi4 as " Error checking write permissions to directory “/etc/mender”  
How to move next?

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**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:** [October 12, 2021, 9:01am UTC](https://hub.mender.io/t/error-during-delta-update/4038/25 "2021-10-12T09:01:24Z")

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> [@abhishek](#):
>
> Also, I could not do mender setup in Rpi4 as " Error checking write permissions to directory “/etc/mender”

This is not surprising, since you are compiling with a read-only root filesystem. `mender setup` simply won’t work in this scenario.

> [@abhishek](#):
>
> But now, mender client available in Rpi4 does not appear in hosted mender server.

The first thing to check is whether there is something in the client logs. Can you post the output from this command on the device:

```bash
journalctl -u mender-client | tail -n 50

```

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<div class="post-metadata">

**Author:** ![abhishek](https://avatars.discourse-cdn.com/v4/letter/a/7ba0ec/32.png) [@abhishek](https://hub.mender.io/u/abhishek)\
**Post date:** [October 12, 2021, 9:14am UTC](https://hub.mender.io/t/error-during-delta-update/4038/26 "2021-10-12T09:14:51Z")

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Got the solution!  
I had accidentally skipped following lines as mentioned in ur post

PREFERRED\_VERSION\_pn-mender = “2.%”  
PREFERRED\_VERSION\_pn-mender-artifact = “3.%”  
PREFERRED\_VERSION\_pn-mender-artifact-native = “3.%”

Thanks

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