ERRORS after upgrade OMV 0.5.59 to OMV 1

I know this issue has been resolved, but I want to report my findings regarding to the NUT graphs not working after upgraded from 0.5.x to 1.x.

I found out it's the rrd definition for NUT had been changed. In OMV 0.5.x, for example, the first few lines output of "rrdtool info /var/lib/rrdcached/db/localhost/nut-ups/percent-charge.rrd" are

filename = "nut-PogoUPS/percent-charge.rrd"
rrd_version = "0003"
step = 10
last_update = 1416408306
header_size = 3300
ds[percent].index = 0
ds[percent].type = "GAUGE"
ds[percent].minimal_heartbeat = 20
ds[percent].min = 0.0000000000e+00
ds[percent].max = 1.0010000000e+02
ds[percent].last_ds = "100.000000"
ds[percent].value = 6.0000000000e+02
ds[percent].unknown_sec = 0

But, in OMV 1.x, the output is

filename = "/var/lib/rrdcached/db/localhost/nut-PogoUPS/percent-charge.rrd"
rrd_version = "0003"
step = 10
last_update = 1416414603
header_size = 3300
ds[value].index = 0
ds[value].type = "GAUGE"
ds[value].minimal_heartbeat = 20
ds[value].min = 0.0000000000e+00
ds[value].max = 1.0010000000e+02
ds[value].last_ds = "100.000000"
ds[value].value = 3.0000000000e+02
ds[value].unknown_sec = 0

You can see that the DS name (data source name) has been changed from "percent" to "value". During upgrade those files were not wiped and recreated, so after upgrade OMV 1.x continues to use those old files. When omv-mkgraph of OMV 1.x tries to create graphs for NUT, it looks for DS name "value" and can't find it when processing rrd files.

rrdtool graph ${IMGDIR}/nut-charge-hour.png --start ${HOURSTART} ${DEFAULTS} --title "${TITLE_NUT_CHARGE}${HOURTITLE}" --slope-mode --upper-limit 100 --lower-limit 0 --rigid --vertical-label Percent    DEF:avg=${DATA}/nut-PogoUPS/percent-charge.rrd:value:AVERAGE    DEF:min=${DATA}/nut-PogoUPS/percent-charge.rrd:value:MIN        DEF:max=${DATA}/nut-PogoUPS/percent-charge.rrd:value:MAX        LINE1:avg${COLOR_NUT_CHARGE}:"Charge"           GPRINT:min:MIN:"%4.2lf Min"     GPRINT:avg:AVERAGE:"%4.2lf Avg"         GPRINT:max:MAX:"%4.2lf Max"     GPRINT:avg:LAST:"%4.2lf Last\l"         COMMENT:"${LASTUPDATE}" >/dev/null

The solution is, as ryecoaaron mentioned, to remove directory /var/lib/rrdcached/db/localhost/nut-ups/ after uninstalling and then reinstall openmediavault-nut. Preferably the uninstall script should remove them for users.