Error when upgrading vb 3.8

[chikuru]

http://www.******.org/vB/install/upgrade_300b6.php?step=2


Database error in vBulletin 3.8.7:

Invalid SQL:
ALTER TABLE attachment ADD INDEX userid (userid);

MySQL Error : Duplicate key name 'userid'
Error Number : 1061
Request Date : Friday, January 29th 2016 @ 05:31:00 PM
Error Date : Friday, January 29th 2016 @ 05:31:00 PM
Script : http://www.*******.org/vB/install/upgrade_300b6.php?step=2
Referrer :
IP Address : ***.***.***.***
Username :
Classname : vB_Database
MySQL Version : 5.5.47-cll

I tried droping userid and still geting same error

[Dave]

Have you tried dropping the index called userid? An index and column are 2 different things.

[chikuru]

Have you tried dropping the index called userid? An index and column are 2 different things.

Whats the query of it?
Thanks Dave!

[Dave]

ALTER TABLE attachment DROP INDEX userid;

If you dropped the column userid, you may face some problems though. The userid column is a mandatory column for the attachment table.

[chikuru]

After running the query, im now getting this:

Database error in vBulletin 3.8.7:

Invalid SQL:
ALTER TABLE attachment ADD INDEX userid (userid);

MySQL Error : Duplicate key name 'userid'
Error Number : 1061
Request Date : Friday, January 29th 2016 @ 06:07:40 PM
Error Date : Friday, January 29th 2016 @ 06:07:40 PM
Script : http://www.*********.org/vB/install/upgrade_300b6.php?step=2
Referrer :
IP Address :
Username :
Classname : vB_Database
MySQL Version : 5.5.47-cll

[Paul M]

What are you upgrading from and to ? - because something is seriously wrong to be running (or trying to run) upgrade_300b6.php?step=2 on a 3.8.7 database.