Joomla upgrade 2.5.28 to 3.5.1: Index column size too large. The maximum column size is 767 bytes.

[cuker]

Hi,
I am trying to update my Joomla 2.5.28 to 3.5.1. I am using the instruction from here: https://docs.joomla.org/Joomla_2.5_to_3.x_Step_by_Step_Migration

Unfortunately, when I run the update from Components - Joomla Update, I have the error:
Index column size too large. The maximum column size is 767 bytes. SQL=ALTER TABLE `#__menu` ENGINE=InnoDB;

I tried to search for the issue in forum / Google, but as I am just a basic Joomla user, I don't know how to fix that. Is it possible to fix my issue in an 'easy' way?

Many thanks for any input.

Regards, Mateusz

[cybersalt]

Of course, you have backed up your 2.5 site right - before trying anything else?

As for "easy", that is always relative to what we know.

I read a bit in this year-old thread (https://forum.joomla.org/viewtopic.php?t=913699) and one suggestion was to run the database fixer and then try again (extensions>manage>update>database>fix)

If that works, great. If not there are some other things to consider and try in that thread.

[cuker]

Of course I have backup. I run DB fix before update, so unfortunately this isn't the solution.
I read the same thread and tried updating Joomla using Custom URL from Richard67, (http://test5.richard-fath.de/list_test1.xml) but then I got the The archive file is corrupt error.

[cybersalt]

Did you try in2city's suggestion - after changing the table prefix to that of your database.

Can you please try running (in PHPMyAdmin or whatever you use on the server) the following:

ALTER TABLE `kdv_menu` DROP KEY `idx_path`;
ALTER TABLE `kdv_menu` ADD KEY `idx_path` (`path`(100));
ALTER TABLE `kdv_users` DROP KEY `idx_name`;
ALTER TABLE `kdv_users` ADD KEY `idx_name` (`name`(100));
ALTER TABLE `kdv_user_keys` DROP KEY `user_id`;
ALTER TABLE `kdv_user_keys` ADD KEY `user_id` (`user_id`(100));