It’s either a problem with the output from NZBHydra or the feed from the indexer (and NZBHydra is just passing it along). Bypassing NZBHydra would tell you where the issue lies (going straight to the indexer), also knowing what is being returned could help us if it’s something we can resolve.
System.FormatException: The string was not recognized as a valid DateTime. There is an unknown word starting at index 0.
at System.DateTimeParse.Parse(String s, DateTimeFormatInfo dtfi, DateTimeStyles styles)
at System.DateTime.Parse(String s, IFormatProvider provider, DateTimeStyles styles)
at NzbDrone.Core.Indexers.XElementExtensions.ParseDate(String dateString) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\XElementExtensions.cs:line 54
at NzbDrone.Core.Indexers.RssParser.GetPublishDate(XElement item) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\RssParser.cs:line 183
at NzbDrone.Core.Indexers.Newznab.NewznabRssParser.GetPublishDate(XElement item) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\Newznab\NewznabRssParser.cs:line 99
at NzbDrone.Core.Indexers.RssParser.ProcessItem(XElement item, ReleaseInfo releaseInfo) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\RssParser.cs:line 149
at NzbDrone.Core.Indexers.Newznab.NewznabRssParser.ProcessItem(XElement item, ReleaseInfo releaseInfo) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\Newznab\NewznabRssParser.cs:line 50
at NzbDrone.Core.Indexers.RssParser.ProcessItem(XElement item) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\RssParser.cs:line 138
at NzbDrone.Core.Indexers.RssParser.ParseResponse(IndexerResponse indexerResponse) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Indexers\RssParser.cs:line 58
This is a problem with the feed that Sonarr is receiving, you’ll need to determine if it’s from the indexer or only NZBHydra and make a change accordingly.
I am also getting these errors using NZBHydra. Disabling Hydra in Sonarr and using the indexers directly appears to fix the issue so it must be something in Hydra.