Additionally, these errors may be found in the cpanel error log:
[2012-04-05 19:18:33 +1000] warn [ssladmin] Unable to produce a valid Apache configuration file. at bin/ssladmin line 201 [2012-04-05 19:18:33 +1000] warn [cpanel] Cpanel::AdminBin::adminrun(ssl) set error in context ssl [2012-04-05 19:18:33 +1000] warn [ssl::install] Encountered error in ssl::install: Error from ssl wrapper: Unable to produce a valid Apache configuration file.
This is caused by an insufficient amount of memory being allocated to the cpanel process. The allocated amount of memory can be changed from within WHM as follows:
1) In the menu on the left, click on "Tweak Settings".
2) In the main frame, click on the "System" tab.
3) Increase the value for "Max cPanel process memory".
An increase of 64MB should generally be enough, but this may vary depending on your system, the amount of domains you have on the system, etc. If an increase of 64MB is inadequate, keep increasing the limit by 32MB increments.