Your $baseurl is most likely misconfigured.

Also make sure the admin and blog are on the same domain, otherwise cookies don't work (that's how cookies are designed).

I use a separate installation for different domains, so yes on same domain. (AND it worked fine before upgrade.)

After searching $baseurl in the forums, I have changed a line in conf/_basic.template.php

$baseurl = 'http://localhost/helioglyphs/blogs/';

No change in behavior.

try clearing your cookies and restarting your browser.

Thanks--have done that a few times, last night and today.

(45 minutes later--edit) I just deleted all cookies AGAIN from both Safari and Firefox, then logged into each.

In Firefox, if I look at my cookies while in Admin, it shows a cookie to expire at end of session; after I hit the BLOG button and look at cookies again, it reports zero cookies. (Wrongly interpreted as end of session?)

Similarly in Safari, checking from inside Admin shows one cookie, but after I hit the BLOG button and check again from the Blog, the cookie is still there: expires Dec 10, 2019! BUT I am logged out.

Bottom line: When I go out to look at the blog ("BLOG" button at upper right of admin page), I am no longer logged in--no "ADMIN" button at upper right of blog page, no EDIT option beside postings. Earlier this afternoon, it also logged me out several times when I hit "Save and Edit" while editing a post--and losing all my changes.

If clearing your cookies after changing $baseurl still doesn't help, your $baseurl is probably still incorrect.

You have a blog running at:
http://helioglyphs.com/argylestreet.php (nice pictures btw ;)

You need
$baseurl = 'http://helioglyphs.com/';

NOT $baseurl = 'http://localhost/helioglyphs/blogs/';
NOT $baseurl = 'http://helioglyphs.com/blogs/';
NOT $baseurl = 'http://www.helioglyphs.com/';

Allow me to insist on the comments in the config file:
* $baseurl is where your blogs reside by default. CHECK THIS CAREFULLY or nothing will work.
* It should be set to the URL where you can find the blog templates and/or the blog stub files,
* that means index.php, blog_b.php, etc.
* Note: Blogs can be in subdirectories of the baseurl. However, no blog should be outside
* of there, or some tricky things may fail (e-g: pingback)

Also, you should probably move everything you have in the /blogs subfolder up one level, so that it's at the same level as your blog stub files (argylestreet.php etc)

It's technically possible to keep b2evo under /blogs but it's a lot more work to configure. I highly recommend you move your files up and configure $baseurl as explained above.

Great--I just found this, will follow up soon. Thank you!

Question before I do follow up: I left blogs in /blogs/ because I am not running a blog as the "home page" of this installation (as I have done elsewhere). The page at helioglyphs.com is an html page that just shows contents as a directory. Do all your instructions still apply in this case?

(30 minutes later--edit) Well, I tried $baseurl = 'http://helioglyphs.com/'; checked in Safari and Firefox: same result. THEN tried $baseurl = 'http://helioglyphs.com/blogs/'; checked in S & F: same result. Changed it back to $baseurl = 'http://helioglyphs.com/'; checked in S & F: same result.

Yes, my advice still applies. Just make sure you delete b2evolution's index.php in order to make sure your index.html gets priority.

Changing $baseurl without moving the files is not enough.

Don't forget to clear cookies everytime you change $baseurl.

Well, it has been a few weeks, but I just moved the contents of my /blogs/ subfolder up one, made sure $baseurl was correct per your advice above in conf/config_basic.php and conf/config_basic.template.php. Had to remove /blogs/ from urls in stub files as well. And now it works perfectly! Thanks again for your help!!

Question, just for understanding: since /blogs/ was part of ALL those addresses originally, would it have worked if I had moved the stub files physically into the /blogs/ folder? (But I like it fine this way.)

Instead of moving files you could set $cookie_path = '/'; in conf/_advanced.php

Yes, it would have worked if you had moved everything under the /blogs folder.