Should not be an issue anywhere except in beta.
There are Flow user talk pages that when moved will produce the error page:
Error An error has occurred. Return to Main Page [V7eJUwpEEaoAAB4-R-wAAAAC] /w/index.php?title=Special:MovePage&action=submit Flow\Exception\FlowException from line 93 of /srv/mediawiki/php-master/extensions/Flow/includes/BoardMover.php: Main discussion workflow for 128669 not found Backtrace: #0 /srv/mediawiki/php-master/extensions/Flow/Hooks.php(1649): Flow\BoardMover->move(integer, Title) #1 /srv/mediawiki/php-master/includes/Hooks.php(195): FlowHooks::onTitleMoveStarting(Title, Title, User) #2 /srv/mediawiki/php-master/includes/MovePage.php(254): Hooks::run(string, array) #3 /srv/mediawiki/php-master/includes/specials/SpecialMovepage.php(589): MovePage->move(User, string, boolean) #4 /srv/mediawiki/php-master/includes/specials/SpecialMovepage.php(128): MovePageForm->doSubmit() #5 /srv/mediawiki/php-master/includes/specialpage/SpecialPage.php(522): MovePageForm->execute(NULL) #6 /srv/mediawiki/php-master/includes/specialpage/SpecialPageFactory.php(583): SpecialPage->run(NULL) #7 /srv/mediawiki/php-master/includes/MediaWiki.php(283): SpecialPageFactory::executePath(Title, RequestContext) #8 /srv/mediawiki/php-master/includes/MediaWiki.php(749): MediaWiki->performRequest() #9 /srv/mediawiki/php-master/includes/MediaWiki.php(521): MediaWiki->main() #10 /srv/mediawiki/php-master/index.php(43): MediaWiki->run() #11 /srv/mediawiki/w/index.php(3): include(string) #12 {main}
The pages where it happens, are very specific - User talk:ET1, ET2, ET3, ET5 (there are more). All those page have template {{Wikitext talk page converted to Flow|archive=User talk:ET13/Archive 1|date=2015-09-10}} indicating that they were converted.
Opting-out and then opting in Flow user talk beta feature does not affect moving pages - no error will be displayed.