**List of steps to reproduce** (step by step, including full links if applicable):
* Install mwcli.
* Set up all containers. ( `mw dev mediawiki create && mw dev mysql create`)
* Clone or download StructuredDiscussion in the 'extensions' directory.
* (If LocalSettings.php exists, then) Append `wfLoadExtension( 'Flow' );` to it.
* Install MediaWiki by executing `mw dev mediawiki install --dbtype mysql`
* (If LocalSettings.php did not exist, then) Append `wfLoadExtension( 'Flow' );` to it and rerun update.php.
* Append `$wgNamespaceContentModels[NS_TALK] = 'flow-board';` to the LocalSettings.php.
* Visit http://default.mediawiki.mwdd.localhost:8080/w/index.php?title=Talk:Main_Page
**What happens?**:
A PHP warning displays.
> Warning: fopen(/var/www/html/w/images/docker/default/tmp/mw-GlobalIdGenerator-UID-88): failed to open stream: No such file or directory in /var/www/html/w/includes/libs/uuid/GlobalIdGenerator.php on line 437
The directory the path indicates doesn't seem to be exist.
```lang=sh
$ mwdev dev mediawiki exec ls /var/www/html/w/images/docker/default
cache
```
**What should have happened instead?**:
An empty Flow board should have been shown when visiting the talk page.
**Software version**:
* mwcli: [[ https://gitlab.wikimedia.org/releng/cli/-/commit/d9c18504919a88c1c41d1312bc30e3b064607700 | d9c1850 ]]
* MediaWiki: 61b534829a
* Flow: 047e88e0
**Other information, etc**:
[[ https://www.mediawiki.org/w/index.php?title=Extension:StructuredDiscussions&oldid=4805444#Post_install | The document on mediawiki.org ]] says:
> You must run "update.php" as the web server user (depends on configuration, but could be e.g. www-data). Otherwise, it can leave temporary `/tmp/mw-UIDGeneratorUUID-UID-xx` files that MediaWiki may be unable to open (task T55791). If you get a "Permission denied" error upon first visiting a Flow board you have to delete these files. Also, update.php will create {{FlowMention}} to support Flow's mention feature in VE (either @ or a toolbar menu provides a convenient auto-complete interface for mentions).