I'm not getting anything in the error logs. I'm thinking it may be some php or apache module I'm missing, because I can reliably re-create the error on a fresh install of ubuntu server with a basic lamp setup.

This is what I currently have:

Quote
[PHP Modules]
calendar
Core
ctype
date
dom
exif
FFI
fileinfo
filter
ftp
gd
gettext
hash
iconv
json
libxml
mbstring
mysqli
mysqlnd
openssl
pcntl
pcre
PDO
pdo_mysql
Phar
posix
random
readline
Reflection
session
shmop
SimpleXML
sockets
sodium
SPL
standard
sysvmsg
sysvsem
sysvshm
tokenizer
xml
xmlreader
xmlwriter
xsl
Zend OPcache
zlib

Apache
access_compat_module (shared)
alias_module (shared)
auth_basic_module (shared)
authn_core_module (shared)
authn_file_module (shared)
authz_core_module (shared)
authz_host_module (shared)
authz_user_module (shared)
autoindex_module (shared)
core_module (static)
deflate_module (shared)
dir_module (shared)
env_module (shared)
filter_module (shared)
http2_module (shared)
http_module (static)
Loaded Modules:
log_config_module (static)
logio_module (static)
mime_module (shared)
mpm_prefork_module (shared)
negotiation_module (shared)
php_module (shared)
reqtimeout_module (shared)
rewrite_module (shared)
setenvif_module (shared)
socache_shmcb_module (shared)
so_module (static)
ssl_module (shared)
status_module (shared)
unixd_module (static)
version_module (static)
watchdog_module (static)