Internal server error on https://musicbrainz.org/release-group/4ccd33c4-e4d2-3cf0-9f9c-b3e8ed68f628/edit
Referrer: https://musicbrainz.org/release-group/4ccd33c4-e4d2-3cf0-9f9c-b3e8ed68f628/edit

Series https://musicbrainz.org/series/01b7f3f9-b3d1-433a-b21e-f54ce2634c3e has 2 members, both Releases.

Trying to add Release Group to it fails,

a) from Release Group edit page as Internal Server Error:

Error:

Caught exception in MusicBrainz::Server::Controller::ReleaseGroup->edit "The edit could not be created. Exception (string): Incorrect entity type for part of series relationship at lib/MusicBrainz/Server/Data/Relationship.pm line 563. at lib/MusicBrainz/Server/Controller.pm line 103. at lib/Sql.pm line 334. at lib/Sql.pm line 334."

Stack trace:

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Time: 2018-03-06 14:28:20 UTC

Host: 5330b658006b

b) from Release Relationship editor page with error message "Incorrect entity type for part of series relationship at lib/MusicBrainz/Server/Data/Relationship.pm line 563, <$fh> line 1."

Several tries failed, but first try on Release level (not Release Group) was accepted.

Under Documentation page https://musicbrainz.org/doc/Series , 1st line reads:"A series is a sequence of separate release groups, releases, [...]" so editors will expect to be able to relate Release Groups by Series. Circumstances given, either the above result is a bug or Relationship Editor should not display Series as viable Relationship for Release Groups.