backend temlate is messed up after upgrade

[fribse]

I'm testing out my website to see how far I can get with an upgrade from 2.5.8.
First of I've removed all components, plugins and modules that were not standard Joomla, but I've of course kept the DB, so that I can reinstall them after the migration.
I've tried a couple of things now (this is all on a test setup, and I have a backup I'm working from, so it's not a problem to go back).
I've tried using the builtin Joomla upgrade, that gave me a site that I couldn't get the backend shown properly, template looks messed up.
I've tried copying in the files, and I've tried applying the 3.0.2 package through the joomla extension installation after doing the upgrade.
I still do not see the backend template, but rather I see some very bad messed up template.
Looking in the folder structure I see 'atomic', 'beez3', 'beez5', 'moviestore' and 'protostar'.
Looking in the joomla template selection, I just see 'BlueStork'.
I've done the DB repair, and no errors there.
What to do?

[fribse]

Ahh, I found the 'Discover' button in all the mess, and that found the missing templates, both front end and backend, and they are installed now, and are working.

[sovainfo]

Trust you mean "Joomla! Update" by "joomla upgrade". It looks like the update didn't go well. You should go back to the situation you started with and try to update using the extension installer. Make sure com_admin #_schemas id 700 knows about the version you start with. Installing the update shouldn't show any errors.

The database->Fix only applies database changes stored in com_admin. It starts where it thinks it left based on id 700 and runs all scripts after that and updates id 700.
So it doesn't fix the database is applies the desired changes to the database.

[Webdongle]

Before upgrading 2.5.8 to 3.0.x there are a few simple steps to take first.

1. Create a backup
2. Use the backup to make a copy of your site(either in a subfolder to a different database or locally on your computer).
3. Set the frontend Template to a standard one(and admin Template to standard if you have a custom one).
4. Disable all 3rd party components extensions and plugins)except Akeeba if you use it)
5. Then apply the update/upgrade
6. Then check which of the third party extensions are compatible with 3.0.x and enable them 1 by 1 and check your site is working each time.
7. If the site fails after enabling an extension then disable it by editing the database and update the extension. Then enable it and see if that helps.

Edited to add numbers to the list.

[sovainfo]

When you number the steps from 1 to 7, the OP has a problem between 5 and 6. Normally step 5 applying the update should be no problem, in this case it is. Don't know what went wrong but do know that when you change methods you should go back to starting position (step 2).

Discovery and Database Fix should only be used for minor corrections. In the situation mentioned above step 5 failed in a big way. Don't consider them minor corrections.

[Webdongle]

When you number the steps from 1 to 7, the OP has a problem between 5 and 6. ...

Often a conflict with a custom Template(or 3rd party extension) ... hence steps 4 and 5. A custom Template (or 3rd party extension) that is incompatible with a version of Joomla can cause a 'time out' that prevents other operations from completing.

... Don't know what went wrong but do know that when you change methods you should go back to starting position (step 2).....

Yep, probably the easiest

...
Discovery and Database Fix should only be used for minor corrections. In the situation mentioned above step 5 failed in a big way. Don't consider them minor corrections.

Yep, if a custom Template (or 3rd party extension) prevented a successful update before there is no guarantee that 'Discovery and Database Fix' will work fully to rectify the problem.

Given that update/upgrade from 2.5 to 3.0 has been successfully tested several times by many ... then any problems are caused by custom Templates, 3rd party extensions, or some glitch on the server.

[fribse]

The approach by webdongle actually brought me quite some way, this is on a testsite, so there's a good backup before trying this out.
Strangely the backend went haywire again suddenly after enabling some items that I didn't suspect, so back to backup.
I've at least now mapped out a few components and plugins that I need to wait for to be 3.x compatible, so good knowledge is being picked up during these trials.
There's no urgency for me on this, I don't mind waiting until 3.5, as we have a very advanced 2.5 site, and I want to make sure that we keep all the functionality.
Only reason for me to start looking into this is a very annoying bug in the breadcrumb / blog layout handling in 2.5.

[Webdongle]

The approach by webdongle actually brought me quite some way, this is on a testsite, so there's a good backup before trying this out.
Strangely the backend went haywire again suddenly after enabling some items that I didn't suspect, so back to backup....

Then use phpMyAdmin ti disable them in the database rather than going through the whole process again.