On my testing environment running latest foundation-2016 (from today), I was monitoring several nodes using RRDtool (with storeByGroup and storeByForeignSource enabled).
After a while, I decided to switch to Newts to test the conversion tool. With OpenNMS stopped, I initialized the cluster and then I executed the conversion tool, but I found that the same error was reported for some of the RRDs (see the attached log).
From the log, there are 23 RRDs that were not updated. The total amount of RRD was 526 (fortunately just a few were effected).
The problem is that if you see the graphs, you can see that some of the metrics have old data, but the ones associated with the affected RRDs are not there, I can only see "new" data.
I can see data for