manual planning error on version 12.0.2

Hello,
So it's normal that we've changed some things in the database, in particular the assignment table with isManual instead of manual to be compatible with the new version of php
ALTER TABLE `${prefix}assignment` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';
run this line on your database > ALTER TABLE `${prefix}assignment` CHANGE `isManual` `manual` int(1) unsigned DEFAULT '0' COMMENT '1';

The following lines may also lead to other errors
ALTER TABLE `${prefix}work` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';
ALTER TABLE `${prefix}plannedwork` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';
ALTER TABLE `${prefix}plannedworkbaseline` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';

Hi

To complete maxca's answer, 
downgrading version would require to restore DB before migration.

So advised step of migration :
- backup DB
- migrate
- test
If test are not correct and you need to downgrade
- downgrade
- restore backup