diff --git a/lib/ExportDestination.php b/lib/ExportDestination.php
index 16f9b15c..ced3ed2b 100644
--- a/lib/ExportDestination.php
+++ b/lib/ExportDestination.php
@@ -92,6 +92,13 @@ public function copyFolder(Folder $folder, string $destinationPath): bool {
 		return true;
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public function setMigratorVersions(array $versions): bool {
+		return $this->addFileContents("migrator_versions.json", json_encode($versions));
+	}
+
 	/**
 	 * {@inheritDoc}
 	 */
diff --git a/lib/ImportSource.php b/lib/ImportSource.php
index ae16fc4f..3a978ce0 100644
--- a/lib/ImportSource.php
+++ b/lib/ImportSource.php
@@ -36,6 +36,11 @@ class ImportSource implements IImportSource {
 
 	private string $path;
 
+	/**
+	 * @var ?array<string, int>
+	 */
+	private ?array $migratorVersions = null;
+
 	public function __construct(string $path) {
 		$this->path = $path;
 		$this->archive = new ZIP($this->path);
@@ -84,6 +89,16 @@ public function copyToFolder(Folder $destination, string $sourcePath): bool {
 		return true;
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getMigratorVersions(): array {
+		if ($this->migratorVersions === null) {
+			$this->migratorVersions = json_decode($this->getFileContents("migrator_versions.json"), true, 512, JSON_THROW_ON_ERROR);
+		}
+		return $this->migratorVersions;
+	}
+
 	/**
 	 * {@inheritDoc}
 	 */
diff --git a/lib/Service/UserMigrationService.php b/lib/Service/UserMigrationService.php
index 6364dd51..364e042d 100644
--- a/lib/Service/UserMigrationService.php
+++ b/lib/Service/UserMigrationService.php
@@ -50,6 +50,8 @@
 class UserMigrationService {
 	use TMigratorBasicVersionHandling;
 
+	protected bool $mandatory = true;
+
 	protected IRootFolder $root;
 
 	protected IConfig $config;
@@ -145,7 +147,7 @@ public function export(IUser $user, ?OutputInterface $output = null): string {
 			$migrator->export($user, $exportDestination, $output);
 			$migratorVersions[$migrator::class] = $migrator->getVersion();
 		}
-		if ($exportDestination->addFileContents("migrator_versions.json", json_encode($migratorVersions)) === false) {
+		if ($exportDestination->setMigratorVersions($migratorVersions) === false) {
 			throw new UserMigrationException("Could not export user information.");
 		}
 
@@ -166,25 +168,18 @@ public function import(string $path, ?OutputInterface $output = null): void {
 			if ($context === null) {
 				throw new UserMigrationException("Failed to get context");
 			}
-			// TODO move this to ImportSource so that migrators can query the versions as well
-			$migrationVersions = json_decode($importSource->getFileContents("migrator_versions.json"), true, 512, JSON_THROW_ON_ERROR);
+			$migratorVersions = $importSource->getMigratorVersions();
 
-			if (!isset($migrationVersions[static::class])) {
-				throw new UserMigrationException("Cannot find version for main class ".static::class);
-			} elseif (!$this->canImport($migrationVersions[static::class])) {
-				throw new UserMigrationException("Version ${migrationVersions[static::class]} for main class ".static::class." is not compatible");
+			if (!$this->canImport($importSource, $migratorVersions[static::class] ?? null)) {
+				throw new UserMigrationException("Version ${$migratorVersions[static::class]} for main class ".static::class." is not compatible");
 			}
 
 			// Check versions
 			foreach ($context->getUserMigrators() as $migratorRegistration) {
 				/** @var IMigrator $migrator */
 				$migrator = $this->container->get($migratorRegistration->getService());
-				if (isset($migrationVersions[$migrator::class])) {
-					if (!$migrator->canImport($migrationVersions[$migrator::class])) {
-						throw new UserMigrationException("Version ${migrationVersions[$migrator::class]} for migrator ".$migrator::class." is not compatible");
-					}
-				} else {
-					$output->writeln("No input data for migrator ".$migrator::class.", ignoring");
+				if (!$migrator->canImport($importSource, $migratorVersions[$migrator::class] ?? null)) {
+					throw new UserMigrationException("Version ${$migratorVersions[$migrator::class]} for migrator ".$migrator::class." is not compatible");
 				}
 			}
 
@@ -197,9 +192,7 @@ public function import(string $path, ?OutputInterface $output = null): void {
 			foreach ($context->getUserMigrators() as $migratorRegistration) {
 				/** @var IMigrator $migrator */
 				$migrator = $this->container->get($migratorRegistration->getService());
-				if (isset($migrationVersions[$migrator::class])) {
-					$migrator->import($user, $importSource, $output);
-				}
+				$migrator->import($user, $importSource, $output, $migratorVersions[$migrator::class] ?? null);
 			}
 
 			$uid = $user->getUID();