PhpStorm fails to start after in-place upgrade: safe rollback without losing settings

Explanation

JetBrains stores each IDE version’s configuration, plugins, caches and logs in a version‑specific directory (e.g. ~/.config/JetBrains/PhpStorm2024.2 on Linux/macOS or %USERPROFILE%\\AppData\\Roaming\\JetBrains\\PhpStorm2024.2 on Windows). An in‑place upgrade leaves the older folder untouched, so your settings are still present. The shared plugin directory may contain plugins that were updated for the newer build; JetBrains will disable any plugin that is incompatible with the running IDE version. A stale .vmoptions file (custom VM options) lives inside the version‑specific config folder and can prevent the IDE from launching if it contains options not understood by the older build.

Steps to roll back safely

1. Close PhpStorm completely (check for background processes).
2. In the JetBrains Toolbox App, locate the previous build of PhpStorm and click the “Install” or “Restore” button to make it available side‑by‑side with the newer version.
3. Remove or rename the config folder of the newer version so the older IDE will not pick it up:
   • Linux/macOS: mv ~/.config/JetBrains/PhpStorm<newVersion> ~/.config/JetBrains/PhpStorm<newVersion>.bak
   • Windows: rename %USERPROFILE%\\AppData\\Roaming\\JetBrains\\PhpStorm<newVersion> to ...\\PhpStorm<newVersion>.bak
4. Delete the custom VM options file from the newer config folder (or from the backup you just created) to avoid launching the older IDE with incompatible JVM options:

   # Linux/macOS
   rm ~/.config/JetBrains/PhpStorm<newVersion>/phpstorm64.vmoptions
   # Windows
   del "%USERPROFILE%\\AppData\\Roaming\\JetBrains\\PhpStorm<newVersion>\\phpstorm64.exe.vmoptions"
   

5. Start the older PhpStorm version from Toolbox. It will automatically use the untouched older config folder (e.g. PhpStorm<oldVersion>) and your settings, plugins and caches should be intact.
6. If the IDE still fails to start, rename the shared plugin directory (e.g. ~/JBServices/PhpStorm/plugins or %APPDATA%\\JetBrains\\PhpStorm<oldVersion>\\plugins) to force a fresh plugin cache, then restart. JetBrains will recreate the folder and load only compatible plugins.
7. Once the older IDE runs stably, you can optionally export settings via File → Manage IDE Settings → Export as a backup, but copying the old config folder directly is more reliable when the IDE starts only intermittently.

When to ask for more detail

If you are unsure whether the failure is due to the VM options file or a plugin, let me know which operating system you are using (Linux, macOS or Windows) so I can confirm the exact paths for the config and plugin directories.