I updated from 2.55 and when I opened Keepass (from the Portableapps UI) I got this error:
HTTP Listener error message https://github.com/pfn/keepasshttp/blob/master/README.md#http-listener-error-message
I deleted the updated version, restored a backup, and ran the upgrade and it did it again.
I compared the new and old versions and the new version:
DELETED a "location - username" folder in the
\PortableApps\KeePassProPortable\App\KeePassProdirectory which contains backups of the .kdbx files. This folder and files are created by the KeeAnywhere addon I think.
It left the
\PortableApps\KeePassProPortable\App\KeePassPro\KeeAnywhereOfflineCachefolder intact, but DELETED the files inside.
I use the extracted version of plugins so that there is no temporary folder & files created. Eg: in
\PortableApps\KeePassProPortable\App\KeePassPro\PluginsI have a folder named "KeePassHttp" with two .dll files. This update created a new
\PortableApps\KeePassProPortable\App\KeePassPro\Plugins. And then subsequently created a new folder and files with the .dll files in
\PortableApps\KeePassProPortable\Data\LocalPluginCache. These duplicates are what causes the error message.
#1 and #2 are huge. If not for this unrelated error leading me to compare the files & folders, this update would have caused permanent data loss.