Turns out the theme was causing the problem, which is strange because it is now the default theme for webmin installs.
Using the "Old Webmin Theme" seemed to have fixed this issue.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I get this error when trying to add an A record. If you need any other stats or have an idea of what it might be, let me know.
Thanks.
*$(@ Friendly error messages. :) Here is the actual error.
Error - Missing Content-Type Header
Undefined subroutine &main::ui_print_header called at /usr/libexec/webmin/mscstyle3/theme.pl line 660.
I suppose I'll try changing the theme as it seems it may not be with the module, but the theme itself.
Turns out the theme was causing the problem, which is strange because it is now the default theme for webmin installs.
Using the "Old Webmin Theme" seemed to have fixed this issue.