Hello,

I was not able to upgrade firmware to version 2.6. Please advise

I downloaded openwrt-ar71xx-generic-carambola2-squashfs-sysupgrade.bin from http://pkg.8devices.com/?dir=carambola2/v2.4/ and it worked fine, but when I tried a package from http://pkg.8devices.com/?dir=carambola2/v2.6/ I received a list of errors after the boot:

[ 16.770000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 16.780000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 16.780000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 16.800000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 16.800000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 16.810000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 16.820000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 16.970000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 16.980000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 17.080000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 17.080000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 17.090000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 17.100000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 17.110000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 17.120000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 17.740000] SQUASHFS error: xz_dec_run error, data probably corrupt
[ 17.740000] SQUASHFS error: squashfs_read_data failed to read block 0x1b5fc6
[ 17.750000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 17.760000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 18.160000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 18.160000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 18.230000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 18.240000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 18.250000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 18.250000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 19.140000] SQUASHFS error: xz_dec_run error, data probably corrupt
[ 19.140000] SQUASHFS error: squashfs_read_data failed to read block 0x1ddc5a
[ 19.150000] SQUASHFS error: Unable to read fragment cache entry [1ddc5a]
[ 19.160000] SQUASHFS error: Unable to read page, block 1ddc5a, size ba34
[ 19.160000] SQUASHFS error: Unable to read fragment cache entry [1ddc5a]
[ 19.170000] SQUASHFS error: Unable to read page, block 1ddc5a, size ba34
[ 19.180000] SQUASHFS error: Unable to read fragment cache entry [1ddc5a]
[ 19.180000] SQUASHFS error: Unable to read page, block 1ddc5a, size ba34
[ 19.190000] SQUASHFS error: Unable to read fragment cache entry [1ddc5a]
[ 19.200000] SQUASHFS error: Unable to read page, block 1ddc5a, size ba34
[ 19.200000] SQUASHFS error: Unable to read fragment cache entry [1ddc5a]
[ 19.210000] SQUASHFS error: Unable to read page, block 1ddc5a, size ba34
[ 19.600000] SQUASHFS error: xz_dec_run error, data probably corrupt
[ 19.600000] SQUASHFS error: squashfs_read_data failed to read block 0x1b5fc6
[ 19.610000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 19.620000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 19.630000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 19.630000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 19.690000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 19.690000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 19.700000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 19.710000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8
[ 19.720000] SQUASHFS error: Unable to read fragment cache entry [1b5fc6]
[ 19.730000] SQUASHFS error: Unable to read page, block 1b5fc6, size 101d8

Also I have something similar when building an image from latest source from git. As I understand it was updated some time ago, because month ago I was successful modified and made a builds without any problems.
[ 5.570000] SQUASHFS error: Unable to read fragment cache entry [136f22]
[ 5.580000] SQUASHFS error: Unable to read page, block 136f22, size fe6c
[ 5.580000] SQUASHFS error: Unable to read fragment cache entry [136f22]
[ 5.590000] SQUASHFS error: Unable to read page, block 136f22, size fe6c
[ 5.600000] SQUASHFS error: Unable to read fragment cache entry [136f22]
[ 5.600000] SQUASHFS error: Unable to read page, block 136f22, size fe6c
[ 5.610000] SQUASHFS error: Unable to read fragment cache entry [136f22]
[ 5.620000] SQUASHFS error: Unable to read page, block 136f22, size fe6c
procd: - preinit -
[ 6.250000] SQUASHFS error: xz_dec_run error, data probably corrupt
[ 6.250000] SQUASHFS error: squashfs_read_data failed to read block 0x2a8fa
[ 6.260000] SQUASHFS error: Unable to read fragment cache entry [2a8fa]
[ 6.270000] SQUASHFS error: Unable to read page, block 2a8fa, size 13b00
procd: - early -
procd: - watchdog -
[ 6.400000] SQUASHFS error: Unable to read fragment cache entry [2a8fa]
[ 6.410000] SQUASHFS error: Unable to read page, block 2a8fa, size 13b00
[ 6.420000] SQUASHFS error: Unable to read fragment cache entry [2a8fa]
[ 6.420000] SQUASHFS error: Unable to read page, block 2a8fa, size 13b00
json_object_from_f[ 6.460000] ath79_wdt: device closed unexpectedly, watchdog timer will not stop!
[ 6.460000] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000100
[ 6.460000]

I already did exactly the same and had the same result but this time it went fine and 2.6 is working fine without errors. Thanks for help
I will try to compile the image from the source and hopefully it will also work.

Unfortunately it was failed, file gdb-linaro-7.6-2013.05.tar.bz2 is not available at openwrt.org.
I found only gdb-linaro-7.2-2011.03-0.tar.bz2. what should I do?

--2014-08-23 14:00:04-- http://downloads.openwrt.org/sources/gd ... 05.tar.bz2
Resolving downloads.openwrt.org (downloads.openwrt.org)... 78.24.191.177
Connecting to downloads.openwrt.org (downloads.openwrt.org)|78.24.191.177|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2014-08-23 14:00:05 ERROR 404: Not Found.

Download failed.
No more mirrors to try - giving up.
make[3]: *** [/home/anton/carambola2/dl/gdb-linaro-7.6-2013.05.tar.bz2] Error 2
make[3]: Leaving directory `/home/anton/carambola2/toolchain/gdb'
make[2]: *** [toolchain/gdb/prepare] Error 2
make[2]: Leaving directory `/home/anton/carambola2'
make[1]: *** [/home/anton/carambola2/staging_dir/toolchain-mips_34kc_gcc-4.8-linaro_uClibc-0.9.33.2/stamp/.toolchain_install] Error 2
make[1]: Leaving directory `/home/anton/carambola2'
make: *** [world] Error 2

I wonder what system are you building? The module that fails to be built is not from our repository. And I think that OpenWRT itself uses a previous version (7.5). Could you please provide the steps that you did?
You can also check out Carambola2 repository in another folder and start again from the beginning.

The commands that you are running seems to be alright. Could you please send the output after you execute them?