I have just spent over one hour troubleshooting my very first "white screen of death". I feel quite proud.
I tried several things and in the end deactivated all plugins (by renaming the plugin folder), then installing them one at a time to see which was the culprit. It was jetpack. When I clicked 'activate' I got this error:
Plugin could not be activated because it triggered a fatal error.
Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 122880 bytes) in ..../oldmankit/wp-content/plugins/jetpack/modules/contact-form/admin.php on line 219
I don't really know what to do about this other than not use jetpack.
I wonder if other people have the same problem. I tried adding this line to wp-config.php, but it doesn't seem to help:
Anyway, I don't really want to increase my memory limit if I don't have to.