Do not show "Adding new attribute failed" when no attributes are set (on a classic theme)

[Marc-pi]

Prerequisites

• I have carried out troubleshooting steps and I believe I have found a bug.
• I have searched for similar bugs in both open and closed issues and cannot find a duplicate.

Describe the bug

follow up to #38815 (i cannot reopen an issue so i create a new one)
follow up to #38755
other people noticed also that the PR did not fix the point
ping @mattsherman / @nathanss / @louwie17

In a woo instance with no attributes set and a classic theme
An annoying popup is displayed (see screenshot below)
i do not see such a error on websites that run FSE only.

Expected behavior

No message should be displayed since the instance do not use attributes at all !

Actual behavior

Just a popup

Steps to reproduce

Just edit a product and wait for the popup to appear

WordPress Environment

Woo 7.9
WP 6.2.2
Avada Theme (yes, i'll move this new customer website to FSE in August)

Isolating the problem

• I have deactivated other plugins and confirmed this bug occurs when only WooCommerce plugin is active.
• This bug happens with a default WordPress theme active, or Storefront.
• I can reproduce this bug consistently using the steps above.

[user-1138]

Same for me... and on a fairly small/vanilla WP/WooC setup. This issue seems to be related to CPU spikes and resulting 503 Service Unavailable errors too - though there is nothing of relevance logged to my WP error_log, or other host level logs.

Per this WordPress support topic others continue to report the issue and associated symptoms.

I'm bumping PHP memory and disabling the WP heartbeat for is_admin() to try and alleviate the issue for now, but something is definitely still amiss here.

WordPress Environment:
WordPress 6.2.2
WooCommerce 7.9.0
Storefront 4.4.1

[mattsherman]

I believe that PR #39502 may help address this issue, as it moved when the empty attribute is created from when the product edit screen first loads to when the "Attributes" tab shown.

@Marc-pi @user-1138 Do you notice anything in the error logs for your site?

[user-1138]

Hey @mattsherman - no nothing. My debug logs are enabled and none of them reveal anything - just the usual deprecation notices and PHP warnings (e.g. undefined variables).

I can stuff about in wp-admin (as the 'Administrator') doing updates, tending to plugins, and checking orders all day long... and I've never once had a 503 error. However since around WC 7.8.0 the actual 'Shop Manager' has copped 503 errors here and there when working with Products - specifically "Simple products" (which is where the "Adding new attribute failed" errors are showing up too). They report that the error has only ever popped up when opening 'old' products (so ones created some time ago - many, many months to years) and then it tends to 503 when saving any changes.

Unfortunately they've just been clicking "Ok" and whacking 'F5' on the 503's until the page comes back, so I've only recently become aware of these issues, and my hosts Domlogs only go back a couple of days, so I can't trawl through them for any hints either.

I am assured however, I will be notified of future such issues and if/when they occur, I'll double check the error_log's and will post relevant Domlog details here too.

[ptepartz]

I had to bump max_input_vars up to 6000, memory limit up to 512mb, execution time up to 600 and post_max_size to 256mb to get the attribute error popup and 503 errors to stop. It had been running flawlessly without those for years and nothing has changed on the website.

[user-1138]

Thanks for the heads up @ptepartz, good to know!