When Plesk is upgraded either from 17.5 or 17.8 with the selected Plesk 12 theme to Obsidian, this theme is preserved after the upgrade, but the layout is completely broken.
- #PPP-45324 "Updating a Plesk instance using a custom skin to Plesk Obsidian no longer results in a broken skin. Instead, the custom skin is replaced with the default Obsidian skin."
- Plesk Obsidian 21 January 2020
If update is not possible for some reason you may try the following
Until a fix becomes available, use the following workaround:
- Log into Plesk;
- Go to Tools & Settings > Schemes and Color themes and change to Onyx or Obsidian theme.