My WordPress 3.4.2 blog website http://dedicto.com/ has hung repeatedly when I attempted to update Jetpack 1.9 to 1.9.1; I don't recall this ever happening before when I tried to update Jetpack or any other plugin (I also use XCloner and Social Login). I recently posted a guest post on behalf of a famous and popular author, including a link to a PDF version of the post available for download, so site traffic is likely to be much higher than usual. (This post is currently the only one on the site, so it is easily accessible from the home page.) The site becomes available again a few minutes after each failed update attempt. The message from trying to visit the site's home page or Dashboard when it is hung is:
Briefly unavailable for scheduled maintenance. Check back in a minute.
After some, but not all, failed update attempts, the following message appears on the Update page:
500: Internal server error This error is generated when a script running on the server could not be implemented or permissions are incorrectly assigned for files or directories Troubleshooting suggestions: Temporarily disable any rewrite rules by renaming your .htaccess file if it exists. Ensure that any CGI or Perl scripts have at least .755. permissions. If trying to run PHP and you get this error, you may have an invalid php.ini in your /cgi-bin, or may be missing your php.dat file in this folder.
When I revisit the Dashboard after the site comes up again, I get the following message in yellow at the top of the screen:
An automated WordPress update has failed to complete - please attempt the update again now.
I have not yet followed any of this boilerplate advice; I doubt seriously whether any of it has anything to do with the actual causes of the crash, especially since I have not changed any of the things it mentions since previous successful updates of plugins, including Jetpack. The only relevant change I am aware of is the posting of the guest post referred to above.