Incompatibility with Data field field type

Hello,
I've followed the steps and am facing the same issue.

Thanks for reporting this.

The BaseFieldDefinition::create($type) is this one in SettingsForm.php?

      foreach ($field_types as $name => $field_type) {
        // Special handling for preconfigured definitions.
        // @see \Drupal\Core\Field\FieldTypePluginManager::getUiDefinitions()
        $type = str_starts_with($name, 'field_ui:') ? $field_type['id'] : $name;
        $field_definition = BaseFieldDefinition::create($type);

We could probably follow the comment here and do something closer to what getUiDefinitions does in FieldTypePluginManager:

  /**
   * {@inheritdoc}
   */
  public function getUiDefinitions() {
    $definitions = $this->getDefinitions();

    // Filter out definitions that can not be configured in Field UI.
    $definitions = array_filter($definitions, function ($definition) {
      return empty($definition['no_ui']);
    });

    // Add preconfigured definitions.
    foreach ($definitions as $id => $definition) {
      if (is_subclass_of($definition['class'], '\Drupal\Core\Field\PreconfiguredFieldUiOptionsInterface')) {
        foreach ($this->getPreconfiguredOptions($definition['id']) as $key => $option) {
          $definitions["field_ui:$id:$key"] = array_intersect_key(
            $option,
            ['label' => 0, 'category' => 1, 'weight' => 1, 'description' => 0]
          ) + $definition;
        }
      }
    }

    return $definitions;
  }

Also, I have documented that this module is not compatible with Data Field on the project page.

Ok, I looked into this more, and I think this may be a problem with the Data Field module, not Field Encrypt.

      foreach ($field_types as $name => $field_type) {
        // Special handling for preconfigured definitions.
        // @see \Drupal\Core\Field\FieldTypePluginManager::getUiDefinitions()
        $type = str_starts_with($name, 'field_ui:') ? $field_type['id'] : $name;
        $field_definition = BaseFieldDefinition::create($type);
        $definitions = $field_definition->getPropertyDefinitions();

In this code, we are pulling in all the field types, including those with PreconfiguredFieldUiOptionsInterface. These preconfigured definitions do NOT include a name property, so the "special handling" gets the actual field type ID so that it can call BaseFieldDefinition::create(), and then we access getPropertyDefinitions().

It seems that DataFieldType relies on field_name being set, but this is not true for PreconfiguredFieldUiOptionsInterface field types.

I knew it. it write down in \datafield\src\Plugin\Field\FieldType\DataFieldItem.php

    // Reset the field storage config property - it will be recalculated
    // when accessed via the property definition getter.
    // @see Drupal\field\Entity\FieldStorageConfig::getPropertyDefinitions()
    // If we don't do this, an exception is thrown during the table update that
    // is very difficult to recover from since the original field tables have
    // already been removed at that point.
    $field_storage_config = $form_state->getBuildInfo()['callback_object']->getEntity();
    $field_storage_config->set('propertyDefinitions', NULL);

You will see the same error on the module having a dynamic subfield like double field, triple field...