Was making changes to one of my Joomla websites' menu system when bumped into a strange issue.
There were types of menu systems, both two levels deep. First menu level in both cases level External URL
Links to Category List layout
Links to Single Article
With first type of menus everything was fine, however, second (linking to single articles) was producing links in format:
index.php/date_time/article i.e. index.php/2012-08-01-14-25-15/article
Checked and doubled checked all aliases for menu items and categories and none of them had any text in aliases.
After some testing and experimenting found where the problem was.
External URL type menu items don't have visible aliases as such. However, it seems that Joomla actually does create aliases for such items.
Let's take an example: Create and save a new External URL type menu item. It will look something like this:
Now try changing Menu Item Type to Text Separator, save changes and see what happens:
Alias field now has date and time from when original External URL type menu item was created. It was actually always there, simply not visible.
Understanding above, solution to the problem is pretty simple: Temporary change menu item type to Text Separator, modify alias to your liking and change type back to External URL.