Trying to upgade from Store Builder v4.8.2.SP2 to v4.9.1

Error is:
"Tech details: Couldn’t complete migration 20180903071847_core_add_product_feature_variant_index.php. Reason: BLOB/TEXT column ‘variant’ used in key specification without a key length.

Completed migrations: 6 out of 11."

Please advise.
Thanks!

Hello!

First of all, please restore the backup that was made prior this upgrade.

The error is caused by the fact that the variant column of the cscart_product_feature_variant_descriptions table in your database was changed from varchar(255) type to text type.

Once the backup is restored, please try to to execute the following SQL query to the database of your store:

ALTER TABLE `cscart_product_feature_variant_descriptions`
ADD INDEX `variant` (`variant`(255));

Once this is done, the upgrade should no longer fail during this migration.