Not able to add more custom fields in Sales Order after update

I have just updated bench and now I am trying to add more custom fields in Sales Order Form (already added so many) via Customize Form. After adding more fields it is giving me error:

OperationalError: (1118, 'Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. This includes storage overhead, check the manual. You have to change some columns to TEXT or BLOBs')

I have updated so many fields via alter table from varchar(140) to blob, but it is still giving me error, and when I remove the newly added field, then system stops giving me errors.

Any idea, how to over come with this?

Ruchin Sharma

The MySQL maximum row size limit of 65,535 bytes is demonstrated in the following InnoDB and MyISAM examples. The limit is enforced regardless of storage engine, even though the storage engine may be capable of supporting larger rows.

Change field type from data to Small Text, Text.