installing system update of samsungtab a6

[gleziel21]

No support single-sku
Supported api:3
E;failed to mount/efs (invalid argument
E;failed to mount /efs(invalid argument)

 

[webworkings]

That doesn't sound like the installing of an update, sounds more like you are trying to install an OS that is newer than your phone allows for. Which personally I would say isn't wise as it can brick the phone.