I'm guessing you haven't run update.php to create the database tables

https://www.mediawiki.org/wiki/Manual:Update.php

Just did it again...Using the browser: /mw-config and the update key.
I don't know if I did something wrong before but it seems to be working now.

Note that I completely deleted the MW site and the DB once and reinstall it completely and got the same outcome.

It seems that it wont work unless I do the /mw-config process

Thanks for your help.

P.S. I think I shouldn't have posted my website address. It won't let me login anymore because of hijacking attempts. I deleted the index.php page.

In T161902#3146921, @TiriPon wrote:

P.S. I think I shouldn't have posted my website address. It won't let me login anymore because of hijacking attempts. I deleted the index.php page.

That's nothing to do with your posting the address. Deleting index.php will just mean your wiki doesn't work

Yes I know. I don't want my wiki to work until login attempts calm down.

So what is not working now?

Well I'm not sure. I was able to create a form using Special:CreateClass. But when I try to use this form It won't let me save it. This time I get "Forbidden You don't have permission to access /index.php on this server."
Then I log out and back in again and then it works.
Then I tried to use the form again to create a second page and I got another error "[WN6FFkg3ugkADqbq9fYAAAHN] 2017-03-31 16:34:30: Fatal exception of type "Wikimedia\Assert\ParameterAssertionException"

I'm not sure of what to conclude. What should I try next?

This now sounds unrelated to Page Forms... does regular editing and saving of pages work?

I don't think I had problems before. But right now I can't because I'm locked out it seems. I am trying to log back in but I get the message "There seems to be a problem with your login session; this action has been canceled as a precaution against session hijacking. Go back to the previous page, reload that page and then try again." and that is why I though I was bombarded with login attempts.

I'll empty my cache and delete cookies try again and let you know.

I just logged in from Firefox (I was in Chrome before)

Tried to create a new page normally and when I saved it I got : Sorry! We could not process your edit due to a loss of session data. You might have been logged out. Please verify that you're still logged in and try again. If it still does not work, try logging out and logging back in, and check that your browser allows cookies from this site.

There is no cookie blocking with my browsers.

Confused!

Emptied cookies and everything in firefox and still can't create a new page.

That's new I was able to do it before.

I don't mind deleting the entire site and DB and try to reinstall and test alot to see if I can reproduce these problems with a clean install.

Should I do it?

https://www.mediawiki.org/wiki/Topic:Pjby0sdeg3e60rfy

I tried the tmp suggestion from that conversation: add session_save_path("tmp"); to the LocalSettings.php file created a tmp folder in the root of the wiki folder. Gave it permission 777. I am still unable to login on my site. I will wait a bit and try again after lunch. Will report back soon.

Session problems in 1.28 are because of T147161: Installer suggests $wgMainCacheType = CACHE_ACCEL, potentially breaking sessions

If you have $wgMainCacheType = CACHE_ACCEL; in LocalSettings.php, be sure to change it to $wgMainCacheType = CACHE_DB; or set to it anyway and see if it works now

Thanks Ciencia_Al_Poder it is working much better now. I have toyed around and did not get any problems related with my initial question.

But...There is still one very weird thing happening.

Still logged in as sysop I can't go to my own User: page.
When I click on it I get a 403 Forbidden You don't have permission to access /index.php on this server.

Only my user page (so far). I don't get it. Tried login off back in, clearing the cookies and even tried from a different physical location (My home)

I tried creating it going to /index.php?title=User:TiriPon&action=edit&redlink=1 and got the same 403...'

Why would it not let me go to my own not existing User: page?

Update: It is actually any User: page. So far I have none. But trying to access/create any page starting by User: gets me to 403 forbidden.

Can it have something to do with me blocking accounts creation?

I finally found somethng on Stackoverflow. Someone had that problem because of the Host's ModSecurity module enabled which I also have with my Host.
I disabled it and it fixed it right away.

The host is warning me to re-enable it because "Without ModSecurity enabled, your domains lose the extra layer of protection that the module provides."

Do anyone knows about ModSecurity and do I really need to have it enabled?
Can I do something else to be able to use my Wiki while still have ModSecurity enabled.

...Should I open a new topic because this is a completely different situation?

I wouldn't bother re-enabling it.

People generally use it as a false sense of security

Understood.

Well, I think I am done and all seems to be working great.

Thanks to everyone! I do appreciate all the help.

Case closed.