wonder what you php max upload and max post size are set to and thats getting in the way?
OK this has given me a VERY BAD EVENING!
First up you hit the nail on the head. Max Upload Size was set to 2MB. The plugin zip is 2.1MB. Real friendly message WP is putting out there. Got rid of all skins and icons except 'defaults' which trimmed the zip down by A WHOLE MEGABYTE and the WP 'add plugin zip' procedure worked perfectly.
Then things 'happened'. Remember – this was on stuff.yellowswordfish.com – up until recently the main forum site with a perfectly working 3.1.4 forum. The first thing is that the upgrade of stuff to Wp2.7 drove it crazy. Getting errors all over the place. The forum works but a lot of the ahah doesn't.
So – I went for an upgrade of the newly installed V4 files. Hit the 'perform upgrade' button and hey – got a blank screen! Firefox/Mac. I simply refreshed the page and this time it worked. But I have a hunch what might be happening here. Well maybe.
Anyway – the upgrade started… AHAH 404 !!!
I really don't get this. the site has been 'AHAH 404' free for the best part of two years! This seems to have more to do with WP2.7 than it does with us. Anyways – going to spend some more time on it but for now, after about 4 hours with this, I need a break!
OK – Final update.
The AHAH 404 error I was getting on my old site upgrade to 4.0 was caused by the fact that my wp-content folder permissions were set to 777. As simple as that. I should have guessed this before and looked so I was just being stupid.
So no big mystery after all.
But the uploading, install and activation of the plugin DOES work if it is below the max upload size threshold.
might be stupid question, but how does 777 cause an ahah error? a lot of folks end up putting that permission on wp-content because their plugins (like wp super cache) tell them to…
They really shouldn't do that. I have been through this before but just forgot. have mentioned it several times on the forum here as well come to that.
A lot of hosts will set the server to refuse a direct URL to a script if the permissions are too open. I guess the theory is that because the permissions are so open it is possible to both plant a malicious script there and run it. the fact that the script was two folders down from wp-content obviously made no difference. I tested this by placing a file that just calls phpinfo in the 'install' folder and that also returned a 404. Setting the wp-content permissions to 755 allows phpinfo to run and also the upgrade script.
This actually seems pretty common and is still the most likely cause of out users getting 404 errors on ajax calls.