Trouble with luci_statistics on gl-ar750

[fantom-x]

Trying to setup collectd (19.07) on gl-ar7500, but getting this error below for anything I enable. I restarted, deleted the database, etc to no avail. I have noticed that /tmp/rrdimg is not being created. Any ideas about what I am doing wrong?

Failed to execute call dispatcher target for entry '/admin/statistics/graph/entropy'.
The called action terminated with an exception:
/usr/lib/lua/luci/statistics/datatree.lua:159: bad argument #1 to 'pairs' (table expected, got nil)
stack traceback:
	[C]: in function 'pairs'
	/usr/lib/lua/luci/statistics/datatree.lua:159: in function 'plugin_instances'
	.../luci/controller/luci_statistics/luci_statistics.lua:187: in function <.../luci/controller/luci_statistics/luci_statistics.lua:142>
	(tail call): ?```

[reinerotto]

Unfortunately I can not directly give you any help, but:
I am using collectd on 18.06.04, only for data collection (CPU, RAM etc.), and txfere info to server. Which works like a charm.
However, I do not use LuCi at all, in custom image. Just the plain/simple collectd scripts.

[fantom-x]

Bad permissions on the rrd directory: some parts of LuCI statistics are not running as root.