Flint 2 running OpenWrt. No space left on device

Installing and Using OpenWrt
1

Hi all,

I am using the Firmware Selector website to create a custom image for my Flint 2. Everything works fine. However, I am trying to update to the latest service pack 24.10.4 and it’s telling me that there is no space left on the device despite the overlay layer being 8GB in size. It seems that the /tmp directory is 100%.

df -h returns

Filesystem Size Used Available Use% Mounted on
/dev/root 33.5M 33.5M 0 100% /rom
tmpfs 493.6M 493.6M 0 100% /tmp
/dev/loop0 7.2G 650.2M 6.6G 9% /overlay
overlayfs:/overlay 7.2G 650.2M 6.6G 9% /
tmpfs 512.0K 0 512.0K 0% /dev

I can download the .bin file to the device just fine under / but when I attempt to upgrade with sysupgrade, I get the error message about there being no space left

Wed Oct 22 19:08:46 BST 2025 upgrade: Image not in /tmp, copying...
cp: write error: No space left on device

How does one overcome this problem?

2

/tmp is a RAM disk. Some application has been storing large files there at runtime. Explore the disk to find what it is. The du (Disk Usage) command is useful here. Or you can just reboot if you don't care to troubleshoot and want to start over.

The sysupgrade process requires free space to hold the new firmware (and existing config files, if you choose to save them) in /tmp.

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3

Thanks a lot @mk24. That makes sense now. I’m using Adguardhome and I suspect it’s trying to save its database etc to /tmp before doing the upgrade.

Is there a way to exclude, for example, /opt/adguardhome/* during the upgrade process but not when you save the config from Luci?

4

Some log filled /tmp file system . Without extra packages

cd /tmp
du -sk * | sort -r -n | head -20

You can also check free command and if you have few hundred MB “available” add that to ramdisk

mount -o remount,size=600M /tmp

Then follow with this on the spot.

Easy cure is to reboot and install eg ncdu and or lsof package to determine what is happening in /tmp

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5

Thank you very much. I looked in /tmp and found a couple of files called sysupgrade.tar and openwrt.bin or something like that. Deleted both and it’s now 2% so I was finally able to upgrade.

Thank you all very much indeed.

6

Use luci-app-attendedsysupgrade next time, install ncdu and lsof for the next time it is full.

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