Today I've learned a big lesson in taking things for granted. Did I mistreat a loved one? Did I assume something about a close friend? No. All I've done is a load of work on an online software project, only to find it's got a debilitating problem, and needs a load of upgrade conversion work to fix it.
In the grand scheme of life, this is of course quite minor. However it's reminded me that you need to check your facts pretty carefully, and don't just assume something is the way you think it is (or should be) - especially if you're working with Open Source software.
Once again: Just because it's written on the Internet, doesn't make it true!