Requires: Voting API (>3.0-beta1) (incompatible with version )

Yes, the -dev release of Fivestar now requires the -dev version of Voting API. See #3131954-8: Port tests to 8.x-1.x

This does work, and does install on the DrupalCI testbot, as you can see from the automated testing output: https://dispatcher.drupalci.org/job/drupal_contrib/191111/console

Giving up is rarely a good solution. The beta1 version of Voting API is more than 1.5 years old, and you will encounter many problems using it. You really do need to try to install the -dev of the Voting API. Likewise, Fivestar has made a lot of improvement recently so it would really be best if you could use the -dev of Fivestar. A new Fivestar release won't be made until there is a new Voting API release.

You didn't mention composer in your original post, and you didn't say where you saw that message.

But as I said installing Fivestar -dev in the testbot works - the testbot uses composer, and the testbot correctly reads the dependency of Voting API > 3.0-beta1 and determines that the -dev version of the Voting API needs to be used. You can see all of this in the link I posted above.

I also tested installing Fivestar -dev on simplytest.me, which uses composer I think, or a combination of drush and composer maybe - they have made a lot of changes recently.

I also tested installing Fivestar -dev using git and enabling the modules either via drush or via the Drupal UI. This also works.

... and I did all these tests BEFORE adding this new requirement to Fivestar. All these things work.

If you are getting an error when installing with composer then you can use composer to find out WHY it can't install something. Fivestar doesn't provide a composer.json, so perhaps there is a problem with the core Drupal composer scaffolding. Or perhaps there is a problem with the Voting API composer.json. Or perhaps there is a bug in the way the new semantic versioning of modules is handled on drupal.org. Or perhaps the problem is how you're using composer on your site.

@Summit If you previously required fivestar@alpha with composer, it would have added votingapi@beta to composer.lock. Since fivestar@dev changes the votingapi req it causes a conflict. You just need to run composer remove drupal/fivestar before running composer require drupal/fivestar:"1.x-dev" and you'll be good to go.

I have Fivestar -dev and Voting API -dev installed and running.

Yes, I also see that error when I run drush updatedb. When it asks Do you wish to continue? (yes/no) [yes]: If you reply "yes" then everything still works.

This appears to be a long-standing bug in core Drupal: #1013302: Composer metadata on dev versions doesn't work in update.php

Also see #3056417: Compatibility Issue with Chaos Tools and #3102426: Drush don't recognize current version of ctools.

To make the error go away, you can replace this line in fivestar.info.yml:
- votingapi:votingapi (>3.0-beta1)
with this:
- votingapi:votingapi
BUT YOU STILL NEED TO USE Voting API -dev ! This will just make the error go away.

I have both VotingAPI 3.x-dev and Fivestar 1.x-dev installed via composer and I confirm that updating with Drush works (if you choose to ignore the warning).

Although, update.php is stuck and doesn't allow for updates due to this warning.

I'll try to post a patch here for the time being so that the issue doesn't affect people who need to deploy and don't have drush access.

Here's the patch.

As explained in #3131954-8: Port tests to 8.x-1.x, which I linked to above, the 1.5 year old beta of Voting API will not work in PHP 7.3, so we need to use the -dev version where that problem has been fixed.

You could help out in the Voting API issue queue in the meantime, to try to get a new release of the Voting API so we don't have to do this, but your patch in #11 will just break sites and will break the Fivestar tests.

I don't think this should be an issue anymore now that Voting API has a new release. If you continue to have this problem with the latest -dev of Fivestar and the new Voting API release, then please post additional information.

No further issues since the new Voting API release.