There is actually a conflict between STATE MACHINE and PLUGIN modules. The following error is generated during installation:

=>Screen error message: The website encountered an unexpected error. Please try again later.

=>Log error messages: InvalidArgumentException: The plugin type definition "plugin_definition_decorator_class" item must valid class name, but "\Drupal\plugin\PluginDefinition\ArrayPluginDefinition" was given and it does not exist. in Drupal\plugin\PluginType\PluginType->__construct() (line 135 of /.../modules/plugin/src/PluginType/PluginType.php).

This was reported as well to the developer of PLUGIN module.

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British-Link created an issue. See original summary.

bojanz’s picture

bojanz commented
Title: Installation error » Integration with Plugin is broken
Priority: Major » Normal

Confirmed.
The ArrayPluginDefinition class doesn't exist, we need to update our integration with Plugin module.

  • bojanz committed 9af9509 on 8.x-1.x 
    Issue #2676620: Integration with Plugin is broken
bojanz’s picture

bojanz commented
Status: Active » Fixed

Pushed a fix, you can try the latest -dev release.

Status: Fixed » Closed (fixed)

Automatically closed - issue fixed for 2 weeks with no activity.