Added by Chris Maeda over 8 years ago
We recently upgraded Redmine from 2.1 to 3.3 and I got tasked with changing some text custom fields to long text.
Details here: http://blog.cmaeda.com/2016/09/changing-custom-field-types-in-redmine.html
Next up is changing list custom fields to version custom fields.
It's actually much simpler. You can just update the custom_fields table, changing the field_format value from 'string' to 'text' for the custom field of your choice (selected by id in the example), like this:
update custom_fields set field_format='text' where id=<...>;
Tested and works great!