I have migrated my server to a faster one. Everything went OK, except now I cannot update my modules.
EDIT: I cannot process any batch operations, as explained below.
On the "/admin/modules/update" page, I select the modules that need to be updated, then click on "Download these updates", I have a partially empty page (see screenshot), where before I had an horizontal blue bar displaying the download progress.
I have the same issue when trying to update the translations.
Also -should it be related- I cannot delete user accounts anymore, see issue here that links to that one: http://drupal.org/node/1821464.
My server is Apache/2.2.16 (Debian), as was the previous server.
Using APC, Varnish and Boost for cache.
Any help much appreciated !