Upgrade issue: MySQL error

[Ali Akbar]

I have upgraded my SugarCRM from 5.2.0h to 5.5.1 successfully without any major issues. Then I tried to upgrade 5.5.1 to 6.0.0. Every process went fine till the commit upgrade step where the following error occurs.

Query Failed:ALTER TABLE cases modify column prodlineid varchar(255) NULL , modify column pp_code varchar(255) NULL , modify column pv_code varchar(255) NULL ::MySQL error 1071: Specified key was too long; max key length is 1000 bytes

I think it might be a problem of tablespace, I don't know

By the way I am using MySQL client version 5.0.37
Does anyone know the fix???????????

[salesagility]

have you made any modifications to the Cases module? ...

[Ali Akbar]

I have added some custom fields in the cases as well as bug modules.