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
```