Version 4.7.1 is broken

Apache event log:

[Wed Nov 23 23:03:32.199501 2016] [:error] [pid 8334] [client 5.45.67.80:50904] PHP Warning: File upload error – unable to create a temporary file in Unknown on line 0
[Wed Nov 23 23:51:11.809789 2016] [:error] [pid 12096] [client 71.9.244.154:50289] PHP Warning: fopen(/tmp/newsletter.4.7.1-ubJu1J.tmp): failed to open stream: No such file or directory in /var/www/benchmarkreviews/site/wp-includes/Requests/Transport/cURL.php on line 138, referer: https://benchmarkreviews.com/wp-admin/update-core.php?action=do-plugin-upgrade
[Wed Nov 23 23:51:12.553347 2016] [:error] [pid 12096] [client 71.9.244.154:50289] PHP Warning: fclose() expects parameter 1 to be resource, boolean given in /var/www/benchmarkreviews/site/wp-includes/Requests/Transport/cURL.php on line 408, referer: https://benchmarkreviews.com/wp-admin/update-core.php?action=do-plugin-upgrade
[Wed Nov 23 23:51:12.623951 2016] [:error] [pid 12096] [client 71.9.244.154:50289] PHP Warning: unlink(/tmp/newsletter.4.7.1-ubJu1J.tmp): No such file or directory in /var/www/benchmarkreviews/site/wp-admin/includes/class-wp-upgrader.php on line 324, referer: https://benchmarkreviews.com/wp-admin/update-core.php?action=do-plugin-upgrade
[Wed Nov 23 23:51:45.686479 2016] [:error] [pid 12414] [client 71.9.244.154:50293] PHP Warning: fopen(/tmp/newsletter.4.7.1-UnaEEi.tmp): failed to open stream: No such file or directory in /var/www/benchmarkreviews/site/wp-includes/Requests/Transport/cURL.php on line 138, referer: https://benchmarkreviews.com/wp-admin/update-core.php?action=do-plugin-upgrade
[Wed Nov 23 23:51:46.241852 2016] [:error] [pid 12414] [client 71.9.244.154:50293] PHP Warning: fclose() expects parameter 1 to be resource, boolean given in /var/www/benchmarkreviews/site/wp-includes/Requests/Transport/cURL.php on line 408, referer: https://benchmarkreviews.com/wp-admin/update-core.php?action=do-plugin-upgrade
[Wed Nov 23 23:51:46.247011 2016] [:error] [pid 12414] [client 71.9.244.154:50293] PHP Warning: unlink(/tmp/newsletter.4.7.1-UnaEEi.tmp): No such file or directory in /var/www/benchmarkreviews/site/wp-admin/includes/class-wp-upgrader.php on line 324, referer: https://benchmarkreviews.com/wp-admin/update-core.php?action=do-plugin-upgrade
[Wed Nov 23 23:53:55.705892 2016] [:error] [pid 12718] [client 71.9.244.154:50336] PHP Warning: fopen(/tmp/newsletter.4.7.1-k5Snih.tmp): failed to open stream: No such file or directory in /var/www/benchmarkreviews/site/wp-includes/Requests/Transport/cURL.php on line 138, referer: https://benchmarkreviews.com/wp-admin/plugin-install.php?tab=plugin-information&plugin=newsletter&section=changelog
[Wed Nov 23 23:53:56.289176 2016] [:error] [pid 12718] [client 71.9.244.154:50336] PHP Warning: fclose() expects parameter 1 to be resource, boolean given in /var/www/benchmarkreviews/site/wp-includes/Requests/Transport/cURL.php on line 408, referer: https://benchmarkreviews.com/wp-admin/plugin-install.php?tab=plugin-information&plugin=newsletter&section=changelog
[Wed Nov 23 23:53:56.291928 2016] [:error] [pid 12718] [client 71.9.244.154:50336] PHP Warning: unlink(/tmp/newsletter.4.7.1-k5Snih.tmp): No such file or directory in /var/www/benchmarkreviews/site/wp-admin/includes/class-wp-upgrader.php on line 324, referer: https://benchmarkreviews.com/wp-admin/plugin-install.php?tab=plugin-information&plugin=newsletter&section=changelog

The problem was that the default php temporary directory (/tmp) was not writable for some reason. Changed permissions, and it works fine now.

How?