Blogger Blogspot Log-On Loop Solved

I have a rule of thumb: if my problem doesn't google, that means it's not a real problem; I've just been stupid somehow.

This one's an exception, and it's tormented me for years. Since the answer doesn't exist online, I'll put it here, where hopefully some people will find it via web search.

Problem
You can't log on to your blog at blogspot.com, only to the back end at blogger.com.

For example.
You choose the "sign in" link atop your blog at xxx.blogspot.com
You're brought to blogger.com, where you log on
You return to xxxx.blogspot.com, where you're still not logged on.
You repeat endlessly, but the problem persists. You can only administer from the back end at blogger.com, never from the front end at xxx.blogspot.com.

Cause
This log-on procedure - where you get sent to a different web domain to sign on - is non-standard. It requires one domain (blogger.com) to pass your log-on cookie to another (blogspot.com), which mimics malevolent behavior many browsers are smart enough to detect and avoid. In short, the blogger.com log-on cookie is not being applied to blogspot.com because Google never should have done it this way.

Solution
Turn off the browser preference that detects and avoids cross-site cookies/tracking. In Safari, go to preferences > Privacy and toggle off "Prevent Cross-Site Tracking".


Update: Ha! Now that I've solved the mystery, if I search for specific search terms from that solution, I do see that it's been noted elsewhere. Unfortunately, this is a case of "bland search term syndrome". Terms like "blogger" and "log-on" produce such a profusion of noisy results that searching is effectively useless. Only if you know the solution can you effectively search for a solution!

So do I leave this posting up? Honestly, it may be no more easily findable than the other buried citations. But I like "bland search term syndrome", so I'll leave it just for that.