Migration error using MySql db

[vsol...@gmail.com]

I configured project using Django server. I had added the required libraries based on requirement. when I tried to migrate Django using Mysql server, I get error:

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

When I searched this error, I found  -->MySQL error: key specification without a key length. but I occur error while migration. 

mysql version - 5.7.20

please help me to find the problem. thanks in advance

[Roberto Rosario]

Which version or fork of Mayan are you using? This error is typical of MySQL when indexing text fields. Mayan doesn't index text fields. All indexed fields are of CHAR 255 type.