I am having a somewhat similar issue. I have upgraded to 2.7 from 2.5.1 and I am having a bit of an issue. My site worked ok at first and then crap hit the fan somewhere. The issue I am having now is that every now and then, but very frequent (7-10 page loads) I will get an error –
Fatal error: Call to undefined method wpdb::has_cap() in /home/nemo-maritime/public_html/wp-admin/includes/schema.php on line 22
on my site. This issue only comes up on the admin side of the site. It happens very randomly, and from pretty much any area of the admin panel I am on – editing comments, writing a post, whatever. After I get this issue/ERROR the url of the site changes to – mydomainname.com/wp-admin/upgrade.php?_wp_http_referer=%2Fwp-admin%2F or whatever page I just came from and got to this error, and changing the page url still gives me this error, any page in the admin section. This issue first started with me getting another fatal error, the error I got previously is – `Warning: require(../wp-load.php) [function.require]: failed to open stream: No such file or directory in /home/nemo-maritime/public_html/wp-admin/upgrade.php on line 18
Fatal error: require() [function.require]: Failed opening required ‘../wp-load.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/nemo-maritime/public_html/wp-admin/upgrade.php on line 18` and another member gave me a solution that it was the load.php that was causing this issue, so I uploaded the new load.php file and this error disappeared, but then I got the new error that is stated on top.
The thing with the site is that I have it set up on two servers, and it loads perfectly on both from the user side. The issue is the admin section. I have googled this issue and people mostly have this while they are upgrading with the plugins folder. I did try to change the plugins folder and name it to something else, but that did not do anything. The weird thing is that this issue disappears on its own after a while…. If I wait a few seconds/minutes and refresh the page, the error stops showing up and its gone for a while and it shows a “No upgrade required. Your WordPress database is already up-to-date!”. Then I’ll go back to taking care of the site and it redirects me to it again, and I have to wait for it to dissapear again by refreshing the page every few seconds. I uploaded my site by following the instructions… the only thing left for me to try is to delete everything from the servers and upload it all over again, but that is a huge pain in the ass so I thought I would look for help here first….. One weird thing that happened during upgrade is that I was not able to change the wp-config.php file, I tried and it gave me an error of Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING in /home/nemo-maritime/public_html/wp-config.php on line 56 so I left it as it was in 2.5, as I am supposed to? Anyways, leaving it fixed my issue with the error…. but now thins thing is giving me problems. I do have another site that is on the same server, and this one was upgraded from 2.6 to 2.7 and I am not having issues with that one at all…..
