Cannot uninstall civivolunteeer

Question

I decided to remove Civivolunteer. Administer > System Settings > Extensions. I disabled Civivolunteer and then Uninstall. Error message: "DB Error: constraint violation" The Civivolunteer extension cannot be enabled or uninstalled. What can I do?

Here is a paste of PART of the log where the error occurs

Aug 28 15:29:07 [info] $Fatal Error Details = Array ( [callback] => Array ( [0] => CRM_Core_Error [1] => handle )

[code] => -3
[message] => DB Error: constraint violation
[mode] => 16
[debug_info] => DELETE FROM `civicrm_uf_group` WHERE `name` = 'volunteer_sign_up' [nativecode=1451 ** Cannot delete or update a parent row: a foreign key constraint fails (`willycg_civicrm`.`civicrm_uf_join`, CONSTRAINT `FK_civicrm_uf_join_uf_group_id` FOREIGN KEY (`uf_group_id`) REFERENCES `civicrm_uf_group` (`id`))]
[type] => DB_Error
[user_info] => DELETE FROM `civicrm_uf_group` WHERE `name` = 'volunteer_sign_up' [nativecode=1451 ** Cannot delete or update a parent row: a foreign key constraint fails (`willycg_civicrm`.`civicrm_uf_join`, CONSTRAINT `FK_civicrm_uf_join_uf_group_id` FOREIGN KEY (`uf_group_id`) REFERENCES `civicrm_uf_group` (`id`))]
[to_string] => [db_error: message="DB Error: constraint violation" code=-3 mode=callback callback=CRM_Core_Error::handle prefix="" info="DELETE FROM `civicrm_uf_group` WHERE `name` = 'volunteer_sign_up' [nativecode=1451 ** Cannot delete or update a parent row: a foreign key constraint fails (`willycg_civicrm`.`civicrm_uf_join`, CONSTRAINT `FK_civicrm_uf_join_uf_group_id` FOREIGN KEY (`uf_group_id`) REFERENCES `civicrm_uf_group` (`id`))]"]

)

Answer 1

I had an identical experience, here's how I fixed it.

Following @Demerit's clue:

1. Using sql:

   update civicrm_uf_group set is_reserved = 0 where name = 'volunteer_sign_up'

2. Now remove the profile (previously, you couldn't via the web interface).

Re-do the uninstall, it now succeeds.

As per the note in the uninstall.sql file, the uninstall process is trying to use a foreign key to remove the profile indirectly, but it's failing. I suspect that profiles got more complicated and this strategy no longer works? Alternatively, perhaps when an early version of the extension gets installed it's subtly different?

Also note that this is actually the last line of the uninstall, so it mostly does uninstall.