Notice: Undefined index: #value in Drupal\smart_date\Plugin\Field\FieldWidget\SmartDateWidgetBase::validateStartEnd() (line 394 of modules/contrib/smart_date/src/Plugin/Field/FieldWidget/SmartDateWidgetBase.php).

I am still having this issue on the newest release of Smart Date (4.0.3) on Drupal 9.5.9, so I rerolled the patch from this issue against the newest module version. After applying the patch I no longer see the error on node save.

I'm still not able to reproduce this issue. I tried on a fresh install of Drupal 9.5.10 with Smart Date 4.0.3. I tried submitting a node with and without field values, with Smart Date and core daterange fields.

I won't be putting any work into reviewing code until I have clear steps to reproduce the problem on a clean install.

Understood that you can’t reproduce, and apologies for the frustration, but multiple people are experiencing this issue. Not sure what more can be said about the steps to reproduce.

Let's maybe try something else: if you install the Smart Date Starter Kit on a fresh install of Drupal, do you see the error? Or does the configuration have to be changed in some way to see it?

I'm seeing this against a new install of 10.0.9.

@EthanT you're seeing this on a fresh install of Drupal, using the Smart Date Starter Kit?

Not sure what you mean by Starter kit. I’m installing via composer and then drush enabling the module.

The Smart Date Starter Kit → provides a known-good set of configuration for working with Smart Date. If you can reproduce the problem using that, then it will help to establish that this is indeed a code-level problem. If you need to change the configuration in order to reproduce the problem, then that will likely provide the extra information I need to reproduce the problem as well.

Updating the patch as I noticed the value for start_date was falling back to default value even when a value was available. I will try to replicate using a fresh Drupal install + Starter Kit and report back as well.

I was able to make this error go away by uninstalling DateTime hide Seconds module. But I also wasn't able to replicate it using the Smart Date starter kit + DateTime hide Seconds on a clean install. SO it might have to do with that module + some other configuration ?

Posting the static patch because using the MR doesn't allow pinning to a specific commit, so anyone can submit pretty much anything and inject it into our codebase IIRC. This also fixed our issue.