I'm trying an upgrade from Drupal 7, for a multisite install.
Tried with two sites a couple of years ago; worked at first.

This time, with one site, just no success.
- which turned out to be primarily because of an issue uploading the Backdrop files.
I saw there was an interruption during transfer; but somehow thought ok. When I later re-uploaded, the website "appeared".
[I have done several Drupal upgrades without this issue]

Also had secondary issue, but solved [as found I'd had same couple of years ago; forgot] by removing non alphaneumeric character in the mysql database password.

Condensed version of the issue I found, just in case anyone happens to have the same in future:

Using a new folder, simply named backdrop - with the Backdrop files, including Sites folder.

It was like this on Home page, and any other page other than update.php it seems, including admin:

Error

Undefined class constant 'LayoutContext::USAGE_TYPE_ALL'

Error message

Error: Undefined class constant 'LayoutContext::USAGE_TYPE_ALL' in Layout->getContexts()

Also:

Warning: file_put_contents(temporary://fileDpzTF4): failed to open stream: "BackdropTemporaryStreamWrapper::stream_open" call failed in file_unmanaged_save_data()

 

 

Most helpful answers

OOOHH.....

Hold on a minute!

I had seen about interrupted connection during upload of Backdrop files; but didn't see an issue.
Tried re uploading some of them; and no result.

But --- after further reupload...

Presto!
Shiny new site appears.

Comments

After some messing about - even finding I'd had one of these errors before, reported here a couple of years ago - now got this message where there should be webpages:

Error: Undefined class constant 'LayoutContext::USAGE_TYPE_ALL' in Layout->getContexts() (line 790 of /usr/www/users/xxx/backdrop/core/modules/layout/includes/layout.class.inc). Dismiss

Undefined class constant 'LayoutContext::USAGE_TYPE_ALL'
 

The error I'd had before involved non alphabetic/numeric character in mysql database password: ok in Drupal, not Backdrop it seems.
Maybe the documentation could indicate this?

After some messing about - even finding I'd had one of these errors before, reported here a couple of years ago - now got this message where there should be webpages:

Error: Undefined class constant 'LayoutContext::USAGE_TYPE_ALL' in Layout->getContexts() (line 790 of /usr/www/users/xxx/backdrop/core/modules/layout/includes/layout.class.inc). Dismiss

Undefined class constant 'LayoutContext::USAGE_TYPE_ALL'
 

The error I'd had before involved non alphabetic/numeric character in mysql database password: ok in Drupal, not Backdrop it seems.
Maybe the documentation could indicate this?

Update.php does report issues; but the wording doesn't indicate any should be catastrophic:

The following updates returned messages
[clicking on link to fix existing file names just takes me to page with Error as per other pages]

system module

Update #1046

image module

Update #1008

  • Imagecache Token module not found. Nothing to be done.

field module

Update #1003

  • Options Element not found. Nothing to be done.

Update #1004

  • Field Formatter Settings not found. Nothing to be done.

As a starting guess, can you reach admin/config/media/file-system and see if the temporary directory is valid? What do you see at admin/structure/layouts?

Thanks; at both these, same as for Home page etc:

Error

Error message

Error: Undefined class constant 'LayoutContext::USAGE_TYPE_ALL' in Layout->getContexts() (line 790 of /usr/www/users/xxx/backdrop/core/modules/layout/includes/layout.class.inc). Dismiss

Undefined class constant 'LayoutContext::USAGE_TYPE_ALL'

OOOHH.....

Hold on a minute!

I had seen about interrupted connection during upload of Backdrop files; but didn't see an issue.
Tried re uploading some of them; and no result.

But --- after further reupload...

Presto!
Shiny new site appears.

Right, see what else I can mess up!

Might be some use, eventually, if more people shift Drupal 7 sites to Backdrop: finding what issues  a non-coding whizz or [my case] a total non-coder may encounter.

I appreciate that you are documenting your process so others can benefit -- thank you!