web setup wizard displays blank page

Question

I was trying to install a free theme (fashionista) using system>web setup wizard>component manager. It completed readiness check and backup steps during installation.

During the next step (new purchase status page) it started installation and showed the text

update application is running

But it took very long and showed the message 'script stopped or not responding'. It gave the option to continue or stop the script. Whatever I choose, the page (and browser) was not responding after that.So I closed the browser.

Then I rolled back the media and code using the following command

magento setup:rollback -c filename -m filename

But now when I go to system>web setup wizard, it opens a blank page(page title 'magento updater', URL- magento/update/index.php ).

How can I resolve it ? Please help.

Answer 1

I ran into the /setup blank page and finally found a fix last night. In my case i was getting a 500 error when i hit the page and in the logs I was getting the error message in my magento error log:

Got error 'PHP message: PHP Fatal error:  Uncaught Exception: Warning:
SessionHandler::read()

Apparently Magento 2 setup will not work if you aren't using default file caching for sessions and the problem in this case is known in Magento 2 and described here Magento 2 Docs Troubleshooting.

What fixed the issue was editing app/etc/env.php and replacing whatever you have for session save with

 'session' =>
  array (
    'save' => 'files',
  ),

From the docs it looks like this issue has been known for some time. It seems like a very simple condition to detect, so it's frustrating that rather than adding something to the codebase that alerts you of the problem if you try to hit /setup, a page was added to the docs.