Does anyone worked around the DIR-850L B1 routers for openwrt support on them ? I'm trying to build one, any help would be appreciated.
D-Link DIR-850L B1 = Realtek RTL8197D SOC = Lexra architecture (unsupported)
See https://openwrt.org/docs/techref/hardware/soc/soc.realtek#lexra for details.
I study all of it, but there is an issue, whenever I try to execute a command on my router it displays this error and halts the system and the I'd have to reboot it and then again same happen, any idea what it could be ?
That would be a question for D-Link's support, not OpenWrt. Your device isn't supported by OpenWrt and (most likely) never will be, we have no experience with the OEM firmware and can't help you with that.