After logging in on website.com/admin, it goes to a page with the SS logo and says "loading..." in the upper left, and just sits there. It doesn't load anything no matter how long I leave it.

I had installed SS and built the website, but then I haven't needed to login for a few months and now it needs some changes and cannot log in (see above)

However, I can log in on website.com/Security/login, but then it just loads a page that says I'm now logged in. When I go back to /admin it just shows the "loading..." page.

I suppose I could ignore that it breaks using /admin, and just use /Security/login to login instead, but how to get to the CMS admin pages?

Error Console shows:

There doesn't seem to be an admin file, so I'm not sure what file(s) to refer to when looking up the line numbers for the undefined Behavior errors

The JQuery errors are merely the closing line of the files:

The Class error is line 1 of the file:

When the "loading..." page loads, the browser shows that the page has fully loaded - the progress bar completes and the throbber stops - so it's not like it's actually gets stuck in the middle of loading. The website itself, which is nothing complicated at the moment, works without a hitch.

Thanks Mauve
The first solution (adding ?isDev=1 to the url) worked great!

The second suggestion, I don't understand what you mean by assets/_combined (is there a file or folder called _combined? I didn't find one), so I set permissions recursively (in case that's what was meant by _combined) in the js folder to 666, but that didn't seem to have any effect.

Anyway, until a permanent solution rears it's head, I'll at least be able to get by with the first solution for the time being...

Hi, I have similar problem: stays on "Loading..." forever. When I try /admin

I get errors like:

Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/css/cms_left.css?m=1346101977
Failed to load resource: the server responded with a status of 403 (Forbidden)
http://silverstripe.varimed.com.pl/cms/css/layout.css?m=1346101978
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/css/typography.css?m=1346101979
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/images/network-save.gif
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/css/cms_right.css?m=1346101977
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/hover.js?m=1346101987
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/lang/en_US.js?m=1346102023
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/LeftAndMain_right.js?m=1346101988
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/SideTabs.js?m=1346101990
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/SideReports.js?m=1346101989
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/LangSelector.js?m=1346101988
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/LeftAndMain.js?m=1346101988
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/LeftAndMain_left.js?m=1346101988
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/ThumbnailStripField.js?m=1346101990
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/TranslationTab.js?m=1346101990
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/CMSMain_left.js?m=1346101987
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/CMSMain.js?m=1346101986
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/CMSMain_right.js?m=1346101987
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/SitetreeAccess.js?m=1346101990
Uncaught ReferenceError: hideLoading is not defined /admin/:645
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/images/closeicon.gif
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/images/loading.gif
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/images/mainmenu/logo.gif
Failed to load resource: the server responded with a status of 403 (Forbidden) http://silverstripe.varimed.com.pl/cms/javascript/tinymce_ssbuttons/editor_plugin_src.js?m=1346102186
Failed to load resource: the server responded with a status of 404 (OK) http://silverstripe.varimed.com.pl/sapphire/thirdparty/tinymce-advcode/langs/pl.js?m=1346102186