I was attempting to undelete the page "List of people by name: Johns" on enwiki to make it easier to import an old edit into its history from the Nostalgia Wikipedia. I received this error as a result:
[WwoLcQpAMFIAAD@ZR1YAAAAC] 2018-05-27 01:35:46: Fatal exception of type "MediaWiki\Storage\IncompleteRevisionException"
I found a way around this without having to undelete any of the edits, and the page doesn't need to be restored. However, I'm reporting this problem in case it points to a deeper issue.
exception.class MediaWiki\Storage\IncompleteRevisionException exception.file /srv/mediawiki/php-1.32.0-wmf.4/includes/Storage/RevisionStore.php:310 exception.message user_text field must not be ''! exception.trace #0 /srv/mediawiki/php-1.32.0-wmf.4/includes/Storage/RevisionStore.php(402): MediaWiki\Storage\RevisionStore->failOnEmpty(string, string) #1 /srv/mediawiki/php-1.32.0-wmf.4/includes/Revision.php(1091): MediaWiki\Storage\RevisionStore->insertRevisionOn(MediaWiki\Storage\RevisionArchiveRecord, Wikimedia\Rdbms\DatabaseMysqli) #2 /srv/mediawiki/php-1.32.0-wmf.4/includes/page/PageArchive.php(678): Revision->insertOn(Wikimedia\Rdbms\DatabaseMysqli) #3 /srv/mediawiki/php-1.32.0-wmf.4/includes/page/PageArchive.php(419): PageArchive->undeleteRevisions(array, boolean, string) #4 /srv/mediawiki/php-1.32.0-wmf.4/includes/specials/SpecialUndelete.php(1147): PageArchive->undelete(array, string, array, boolean, User) #5 /srv/mediawiki/php-1.32.0-wmf.4/includes/specials/SpecialUndelete.php(201): SpecialUndelete->undelete() #6 /srv/mediawiki/php-1.32.0-wmf.4/includes/specialpage/SpecialPage.php(522): SpecialUndelete->execute(NULL) #7 /srv/mediawiki/php-1.32.0-wmf.4/includes/specialpage/SpecialPageFactory.php(568): SpecialPage->run(NULL) #8 /srv/mediawiki/php-1.32.0-wmf.4/includes/MediaWiki.php(288): SpecialPageFactory::executePath(Title, RequestContext) #9 /srv/mediawiki/php-1.32.0-wmf.4/includes/MediaWiki.php(861): MediaWiki->performRequest() #10 /srv/mediawiki/php-1.32.0-wmf.4/includes/MediaWiki.php(524): MediaWiki->main() #11 /srv/mediawiki/php-1.32.0-wmf.4/index.php(42): MediaWiki->run() #12 /srv/mediawiki/w/index.php(3): include(string) #13 {main} exception_id WwoLcQpAMFIAAD@ZR1YAAAAC exception_url /w/index.php?title=Special:Undelete&action=submit