Issue #3245655 by kunal.sachdev, tedbow: Do not support updating FROM a -dev version

src/Validator/UpdateVersionValidator.php

@@ -67,6 +67,14 @@ class UpdateVersionValidator implements EventSubscriberInterface {
       $error = ValidationResult::createError($messages);
       $event->addValidationResult($error);
     }
+    elseif ($from_version->getVersionExtra() === 'dev') {
+      $messages[] = $this->t('Drupal cannot be automatically updated from its current version, @from_version, to the recommended version, @to_version, because automatic updates from a dev version to any other version are not supported.', [
+        '@to_version' => $to_version_string,
+        '@from_version' => $from_version_string,
+      ]);
+      $error = ValidationResult::createError($messages);
+      $event->addValidationResult($error);
+    }
     elseif ($from_version->getMajorVersion() !== $to_version->getMajorVersion()) {
       $messages[] = $this->t('Drupal cannot be automatically updated from its current version, @from_version, to the recommended version, @to_version, because automatic updates from one major version to another are not supported.', [
         '@to_version' => $to_version_string,

tests/src/Kernel/ReadinessValidation/UpdateVersionValidatorTest.php

@@ -59,4 +59,13 @@ class UpdateVersionValidatorTest extends AutomaticUpdatesKernelTestBase {
     $this->assertCheckerResultsFromManager([$result], TRUE);
   }
 
+  /**
+   * Tests a current version that is a dev version.
+   */
+  public function testUpdatesFromDevVersion(): void {
+    $this->setCoreVersion('9.8.0-dev');
+    $result = ValidationResult::createError(['Drupal cannot be automatically updated from its current version, 9.8.0-dev, to the recommended version, 9.8.1, because automatic updates from a dev version to any other version are not supported.']);
+    $this->assertCheckerResultsFromManager([$result], TRUE);
+  }
+
 }