Hi

not long ago I purchased a license for my employer. Since then we've done a test install that produced some rather unwanted side-effects. 

While the slider itself worked post-install. and we fixed an Advagg related issue, we got another more serious side-effects. Activation of md slider produced a number of issues, one being that drupal /modules stopped working entirely. 

the site is using among other Features and also translations.  

When cache clears we found the following errors

⋊> ~/S/corp on develop ◦ drush @corp.local cc all                                                                                                                                                                               14:13:17
exception 'FieldException' with message 'Attempt to create field name <em class="placeholder">cer_bidirectional</em> which already exists and is active.' in /vagrant/drupal/current/modules/field/field.crud.inc:85                   [error]
Stack trace:
#0 [internal function]: field_create_field(Array, 0)
#1 /vagrant/drupal/current/sites/all/modules/contrib/cer/cer.install(52): array_walk(Array, 'field_create_fi...')
#2 [internal function]: cer_install()
#3 /vagrant/drupal/current/includes/module.inc(922): call_user_func_array('cer_install', Array)
#4 /vagrant/drupal/current/sites/all/modules/contrib/features_override/features_override.export.inc(171): module_invoke('cer', 'install')
#5 /vagrant/drupal/current/sites/all/modules/contrib/features_override/features_override.export.inc(93): features_override_module_component_overrides('cer', 'md_slider', false, true)
#6 /vagrant/drupal/current/sites/all/modules/contrib/features_override/features_override.features.inc(176): features_override_get_overrides('node')
#7 [internal function]: features_overrides_features_export_render('corpsegments', Array, NULL, 'features_overri...')
#8 /vagrant/drupal/current/sites/all/modules/contrib/features/features.module(594): call_user_func_array('features_overri...', Array)
#9 /vagrant/drupal/current/sites/all/modules/contrib/features/features.export.inc(747): features_invoke('features_overri...', 'features_export...', 'corpsegments', Array, NULL)
#10 /vagrant/drupal/current/sites/all/modules/contrib/features/features.export.inc(680): features_get_normal('features_overri...', 'corpsegments', true)
#11 /vagrant/drupal/current/sites/all/modules/contrib/features/features.export.inc(918): features_get_signature('normal', 'corpsegments', 'features_overri...', true)
#12 /vagrant/drupal/current/sites/all/modules/contrib/features/features.module(966): features_get_component_states(Array, true, true)
#13 /vagrant/drupal/current/sites/all/modules/contrib/features/features.module(1026): _features_restore('rebuild', Array)
#14 /vagrant/drupal/current/sites/all/modules/contrib/features/features.module(275): features_rebuild()
#15 [internal function]: features_flush_caches()
#16 /vagrant/drupal/current/includes/module.inc(951): call_user_func_array('features_flush_...', Array)
#17 /vagrant/drupal/current/includes/common.inc(7626): module_invoke_all('flush_caches')
#18 /usr/lib/composer/vendor/drush/drush/commands/core/drupal/cache.inc(99): drupal_flush_all_caches()
#19 /usr/lib/composer/vendor/drush/drush/includes/drush.inc(722): drush_cache_clear_both()
#20 /usr/lib/composer/vendor/drush/drush/includes/drush.inc(709): drush_call_user_func_array('drush_cache_cle...', Array)
#21 /usr/lib/composer/vendor/drush/drush/commands/core/cache.drush.inc(144): drush_op('drush_cache_cle...')
#22 [internal function]: drush_cache_command_clear('all')
#23 /usr/lib/composer/vendor/drush/drush/includes/command.inc(361): call_user_func_array('drush_cache_com...', Array)
#24 /usr/lib/composer/vendor/drush/drush/includes/command.inc(212): _drush_invoke_hooks(Array, Array)
#25 [internal function]: drush_command('all')
#26 /usr/lib/composer/vendor/drush/drush/includes/command.inc(180): call_user_func_array('drush_command', Array)
#27 /usr/lib/composer/vendor/drush/drush/lib/Drush/Boot/BaseBoot.php(64): drush_dispatch(Array)
#28 /usr/lib/composer/vendor/drush/drush/drush.php(70): Drush\Boot\BaseBoot->bootstrap_and_dispatch()
#29 /usr/lib/composer/vendor/drush/drush/drush.php(11): drush_main()
#30 {main}

We have also seen a PDOException like documented here. https://www.drupal.org/node/1103008

Thanks