I have the same problem:
I upgraded to WordPress 3.8 and looking around I opened
“Apearance –> Customize”
and then hit
“Close”
without making any changes.
Now my website is down and I can’t access wp-admin. When I try I get;
{“success”:”-1″,”alert”:”Cannot write style-custom.css file, you may try setting the style-custom.css file permission to 755 or 777 to solved this. ( If file does not exists, you have to create it yourself )”}
I found that I have four themes listed in;
/var/www/wp-content/themes
1) bluediamond-v 1_05 (This is the only one that has the “style-custom.css” file
2) twentyfourteen
3) twentythirteen
4) twentytwelve
I changed the existing “style-custom.css” file permissions to 755. I still can’t access wp-admin or the website – I continue to get the same alert.
