Django - MySQL (1170, "BLOB/TEXT column 'my_column' used in key specification without a key length

Question

I've updated the Django model field from CharField to TextField.

I got the below error while applying migrations in MySQL.

django.db.utils.OperationalError: (1170, "BLOB/TEXT column 'my_column' used in key specification without a key length")

Django version: 2.2.2 Note: This column in included in unique_together in Meta.

Below answers not worked/ not related:

• how-do-i-specify-an-index-for-a-textfield
• Django MySQL - Setting an index on a Textfield