Hi, unfortunately I have the same problem as described here and do not know how to get ahead 
Login via SSH works fine, but I cant get to the web interface > JSON.parse: unexpected character at line 1 column 1 of the JSON data
I have flashed to the latest version via medkit, but that did not help either.
root@turris:~# cat /etc/os-release
NAME="TurrisOS"
VERSION="6.3.2"
ID="turrisos"
ID_LIKE="lede openwrt"
PRETTY_NAME="TurrisOS 6.3.2"
VERSION_ID="6.3.2"
HOME_URL="https://www.turris.cz/"
BUG_URL="https://gitlab.nic.cz/groups/turris/-/issues/"
SUPPORT_URL="https://www.turris.cz/support/"
BUILD_ID="r16847+124-f8282da11e"
OPENWRT_BOARD="mvebu/cortexa9"
OPENWRT_ARCH="arm_cortex-a9_vfpv3-d16"
OPENWRT_TAINTS="busybox"
OPENWRT_DEVICE_MANUFACTURER="CZ.NIC"
OPENWRT_DEVICE_MANUFACTURER_URL="https://www.turris.cz/"
OPENWRT_DEVICE_PRODUCT="Turris Omnia"
OPENWRT_DEVICE_REVISION="v0"
OPENWRT_RELEASE="TurrisOS 6.3.2 f8282da11ee77c36acb1bd94c99b76ce13257ab9"