Merge pull request #59677 from nextcloud/fix/57340/owncloud-migration-appconfig-userconfig

fix(appconfig,userconfig): restore pre-migration fallback for ownCloud migration

lib/private/AppConfig.php

@@ -67,6 +67,16 @@ class AppConfig implements IAppConfig {
 	private array $valueTypes = [];  // type for all config values
 	private bool $fastLoaded = false;
 	private bool $lazyLoaded = false;
+	/**
+	 * Tracks whether the NC-only columns (`type`, `lazy`) exist in the `appconfig` table.
+	 * Set to false on first load when a DBException::REASON_INVALID_FIELD_NAME is caught,
+	 * which happens during an ownCloud → Nextcloud migration before the schema steps have run.
+	 *
+	 * Every SELECT that reads those columns and every INSERT/UPDATE that writes them must
+	 * guard with `if ($this->migrationCompleted)` so they degrade gracefully.
+	 * If you add a new query that touches NC-only columns, add the same guard.
+	 */
+	private bool $migrationCompleted = true;
 	/** @var array<string, array{entries: array<string, Entry>, aliases: array<string, string>, strictness: Strictness}> ['app_id' => ['strictness' => ConfigLexiconStrictness, 'entries' => ['config_key' => ConfigLexiconEntry[]]] */
 	private array $configLexiconDetails = [];
 	private bool $ignoreLexiconAliases = false;
@@ -854,10 +864,12 @@ class AppConfig implements IAppConfig {
 				$insert = $this->connection->getQueryBuilder();
 				$insert->insert('appconfig')
 					->setValue('appid', $insert->createNamedParameter($app))
-					->setValue('lazy', $insert->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
-					->setValue('type', $insert->createNamedParameter($type, IQueryBuilder::PARAM_INT))
 					->setValue('configkey', $insert->createNamedParameter($key))
 					->setValue('configvalue', $insert->createNamedParameter($value));
+				if ($this->migrationCompleted) {
+					$insert->setValue('lazy', $insert->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
+						->setValue('type', $insert->createNamedParameter($type, IQueryBuilder::PARAM_INT));
+				}
 				$insert->executeStatement();
 				$inserted = true;
 			} catch (DBException $e) {
@@ -917,10 +929,12 @@ class AppConfig implements IAppConfig {
 			$update = $this->connection->getQueryBuilder();
 			$update->update('appconfig')
 				->set('configvalue', $update->createNamedParameter($value))
-				->set('lazy', $update->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
-				->set('type', $update->createNamedParameter($type, IQueryBuilder::PARAM_INT))
 				->where($update->expr()->eq('appid', $update->createNamedParameter($app)))
 				->andWhere($update->expr()->eq('configkey', $update->createNamedParameter($key)));
+			if ($this->migrationCompleted) {
+				$update->set('lazy', $update->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
+					->set('type', $update->createNamedParameter($type, IQueryBuilder::PARAM_INT));
+			}
 
 			$update->executeStatement();
 		}
@@ -1383,23 +1397,39 @@ class AppConfig implements IAppConfig {
 
 		// Otherwise no cache available and we need to fetch from database
 		$qb = $this->connection->getQueryBuilder();
-		$qb->from('appconfig')
+		$qb->from('appconfig');
-			->select('appid', 'configkey', 'configvalue', 'type');
 
-		if ($lazy === false) {
+		if (!$this->migrationCompleted) {
-			$qb->where($qb->expr()->eq('lazy', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT)));
+			$qb->select('appid', 'configkey', 'configvalue');
 		} else {
-			if ($loadLazyOnly) {
+			$qb->select('appid', 'configkey', 'configvalue', 'type');
-				$qb->where($qb->expr()->eq('lazy', $qb->createNamedParameter(1, IQueryBuilder::PARAM_INT)));
+
+			if ($lazy === false) {
+				$qb->where($qb->expr()->eq('lazy', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT)));
+			} else {
+				if ($loadLazyOnly) {
+					$qb->where($qb->expr()->eq('lazy', $qb->createNamedParameter(1, IQueryBuilder::PARAM_INT)));
+				}
+				$qb->addSelect('lazy');
 			}
-			$qb->addSelect('lazy');
 		}
 
-		$result = $qb->executeQuery();
+		try {
+			$result = $qb->executeQuery();
+		} catch (DBException $e) {
+			if ($e->getReason() !== DBException::REASON_INVALID_FIELD_NAME || !$this->migrationCompleted) {
+				throw $e;
+			}
+			// columns 'type' and 'lazy' don't exist yet (ownCloud migration)
+			$this->migrationCompleted = false;
+			$this->loadConfig($app, $lazy);
+			return;
+		}
+
 		$rows = $result->fetchAll();
 		foreach ($rows as $row) {
 			// most of the time, 'lazy' is not in the select because its value is already known
-			if ($lazy && ((int)$row['lazy']) === 1) {
+			if ($this->migrationCompleted && $lazy && ((int)$row['lazy']) === 1) {
 				$this->lazyCache[$row['appid']][$row['configkey']] = $row['configvalue'] ?? '';
 			} else {
 				$this->fastCache[$row['appid']][$row['configkey']] = $row['configvalue'] ?? '';

lib/private/Config/UserConfig.php

@@ -70,6 +70,16 @@ class UserConfig implements IUserConfig {
 	private array $configLexiconDetails = [];
 	private bool $ignoreLexiconAliases = false;
 	private array $strictnessApplied = [];
+	/**
+	 * Tracks whether the NC-only columns (`type`, `lazy`, `flags`, `indexed`) exist in the
+	 * `preferences` table. Set to false on first load when a DBException::REASON_INVALID_FIELD_NAME
+	 * is caught, which happens during an ownCloud → Nextcloud migration before the schema steps run.
+	 *
+	 * Every SELECT that reads those columns and every INSERT/UPDATE that writes them must
+	 * guard with `if ($this->migrationCompleted)` so they degrade gracefully.
+	 * If you add a new query that touches NC-only columns, add the same guard.
+	 */
+	private bool $migrationCompleted = true;
 
 	public function __construct(
 		protected IDBConnection $connection,
@@ -1183,12 +1193,14 @@ class UserConfig implements IUserConfig {
 				$insert->insert('preferences')
 					->setValue('userid', $insert->createNamedParameter($userId))
 					->setValue('appid', $insert->createNamedParameter($app))
-					->setValue('lazy', $insert->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
-					->setValue('type', $insert->createNamedParameter($type->value, IQueryBuilder::PARAM_INT))
-					->setValue('flags', $insert->createNamedParameter($flags, IQueryBuilder::PARAM_INT))
-					->setValue('indexed', $insert->createNamedParameter($indexed))
 					->setValue('configkey', $insert->createNamedParameter($key))
 					->setValue('configvalue', $insert->createNamedParameter($value));
+				if ($this->migrationCompleted) {
+					$insert->setValue('lazy', $insert->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
+						->setValue('type', $insert->createNamedParameter($type->value, IQueryBuilder::PARAM_INT))
+						->setValue('flags', $insert->createNamedParameter($flags, IQueryBuilder::PARAM_INT))
+						->setValue('indexed', $insert->createNamedParameter($indexed));
+				}
 				$insert->executeStatement();
 				$inserted = true;
 			} catch (DBException $e) {
@@ -1240,13 +1252,15 @@ class UserConfig implements IUserConfig {
 			$update = $this->connection->getQueryBuilder();
 			$update->update('preferences')
 				->set('configvalue', $update->createNamedParameter($value))
-				->set('lazy', $update->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
-				->set('type', $update->createNamedParameter($type->value, IQueryBuilder::PARAM_INT))
-				->set('flags', $update->createNamedParameter($flags, IQueryBuilder::PARAM_INT))
-				->set('indexed', $update->createNamedParameter($indexed))
 				->where($update->expr()->eq('userid', $update->createNamedParameter($userId)))
 				->andWhere($update->expr()->eq('appid', $update->createNamedParameter($app)))
 				->andWhere($update->expr()->eq('configkey', $update->createNamedParameter($key)));
+			if ($this->migrationCompleted) {
+				$update->set('lazy', $update->createNamedParameter(($lazy) ? 1 : 0, IQueryBuilder::PARAM_INT))
+					->set('type', $update->createNamedParameter($type->value, IQueryBuilder::PARAM_INT))
+					->set('flags', $update->createNamedParameter($flags, IQueryBuilder::PARAM_INT))
+					->set('indexed', $update->createNamedParameter($indexed));
+			}
 
 			$update->executeStatement();
 		}
@@ -1810,25 +1824,41 @@ class UserConfig implements IUserConfig {
 
 		$qb = $this->connection->getQueryBuilder();
 		$qb->from('preferences');
-		$qb->select('appid', 'configkey', 'configvalue', 'type', 'flags');
 		$qb->where($qb->expr()->eq('userid', $qb->createNamedParameter($userId)));
 
-		// we only need value from lazy when loadConfig does not specify it
+		if (!$this->migrationCompleted) {
-		if ($lazy !== null) {
+			$qb->select('appid', 'configkey', 'configvalue');
-			$qb->andWhere($qb->expr()->eq('lazy', $qb->createNamedParameter($lazy ? 1 : 0, IQueryBuilder::PARAM_INT)));
 		} else {
-			$qb->addSelect('lazy');
+			$qb->select('appid', 'configkey', 'configvalue', 'type', 'flags');
+
+			// we only need value from lazy when loadConfig does not specify it
+			if ($lazy !== null) {
+				$qb->andWhere($qb->expr()->eq('lazy', $qb->createNamedParameter($lazy ? 1 : 0, IQueryBuilder::PARAM_INT)));
+			} else {
+				$qb->addSelect('lazy');
+			}
+		}
+
+		try {
+			$result = $qb->executeQuery();
+		} catch (DBException $e) {
+			if ($e->getReason() !== DBException::REASON_INVALID_FIELD_NAME || !$this->migrationCompleted) {
+				throw $e;
+			}
+			// columns 'type', 'lazy', 'flags', 'indexed' don't exist yet (ownCloud migration)
+			$this->migrationCompleted = false;
+			$this->loadConfig($userId, $lazy);
+			return;
 		}
 
-		$result = $qb->executeQuery();
 		$rows = $result->fetchAll();
 		foreach ($rows as $row) {
-			if (($row['lazy'] ?? ($lazy ?? 0) ? 1 : 0) === 1) {
+			if ($this->migrationCompleted && (($row['lazy'] ?? ($lazy ?? 0) ? 1 : 0) === 1)) {
 				$this->lazyCache[$userId][$row['appid']][$row['configkey']] = $row['configvalue'] ?? '';
 			} else {
 				$this->fastCache[$userId][$row['appid']][$row['configkey']] = $row['configvalue'] ?? '';
 			}
-			$this->valueDetails[$userId][$row['appid']][$row['configkey']] = ['type' => ValueType::from((int)($row['type'] ?? 0)), 'flags' => (int)$row['flags']];
+			$this->valueDetails[$userId][$row['appid']][$row['configkey']] = ['type' => ValueType::from((int)($row['type'] ?? 0)), 'flags' => (int)($row['flags'] ?? 0)];
 		}
 		$result->closeCursor();
 		$this->setAsLoaded($userId, $lazy);

tests/lib/AppConfigMigrationFallbackTest.php

@@ -0,0 +1,185 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace Test;
+
+use Doctrine\DBAL\Exception\InvalidFieldNameException;
+use OC\AppConfig;
+use OC\Config\ConfigManager;
+use OC\Config\PresetManager;
+use OC\DB\Exceptions\DbalException;
+use OC\Memcache\Factory as CacheFactory;
+use OCP\DB\Exception as DBException;
+use OCP\DB\IResult;
+use OCP\DB\QueryBuilder\IExpressionBuilder;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IConfig;
+use OCP\IDBConnection;
+use OCP\Security\ICrypto;
+use PHPUnit\Framework\MockObject\MockObject;
+use Psr\Log\LoggerInterface;
+
+/**
+ * Tests the ownCloud migration fallback in AppConfig.
+ *
+ * When migrating from ownCloud, the appconfig table lacks 'type' and 'lazy'
+ * columns. AppConfig::loadConfig() must catch the resulting DBException and
+ * retry with a query that only selects columns present in ownCloud's schema.
+ */
+class AppConfigMigrationFallbackTest extends TestCase {
+	private IConfig&MockObject $config;
+	private IDBConnection&MockObject $connection;
+	private ConfigManager&MockObject $configManager;
+	private PresetManager&MockObject $presetManager;
+	private LoggerInterface&MockObject $logger;
+	private ICrypto&MockObject $crypto;
+	private CacheFactory&MockObject $cacheFactory;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->connection = $this->createMock(IDBConnection::class);
+		$this->config = $this->createMock(IConfig::class);
+		$this->configManager = $this->createMock(ConfigManager::class);
+		$this->presetManager = $this->createMock(PresetManager::class);
+		$this->logger = $this->createMock(LoggerInterface::class);
+		$this->crypto = $this->createMock(ICrypto::class);
+		$this->cacheFactory = $this->createMock(CacheFactory::class);
+	}
+
+	private function getAppConfig(): AppConfig {
+		$this->config->method('getSystemValueBool')
+			->with('cache_app_config', true)
+			->willReturn(true);
+		$this->cacheFactory->method('isLocalCacheAvailable')->willReturn(false);
+
+		return new AppConfig(
+			$this->connection,
+			$this->config,
+			$this->configManager,
+			$this->presetManager,
+			$this->logger,
+			$this->crypto,
+			$this->cacheFactory,
+		);
+	}
+
+	private function createInvalidFieldNameException(): DBException {
+		$driverException = $this->createMock(\Doctrine\DBAL\Driver\Exception::class);
+		$dbalException = new InvalidFieldNameException($driverException, null);
+		return DbalException::wrap($dbalException);
+	}
+
+	private function createMockQueryBuilder(): IQueryBuilder&MockObject {
+		$expression = $this->createMock(IExpressionBuilder::class);
+		$qb = $this->createMock(IQueryBuilder::class);
+		$qb->method('from')->willReturn($qb);
+		$qb->method('select')->willReturn($qb);
+		$qb->method('addSelect')->willReturn($qb);
+		$qb->method('where')->willReturn($qb);
+		$qb->method('andWhere')->willReturn($qb);
+		$qb->method('set')->willReturn($qb);
+		$qb->method('expr')->willReturn($expression);
+		$qb->method('insert')->willReturn($qb);
+		$qb->method('setValue')->willReturn($qb);
+		$qb->method('createNamedParameter')->willReturn('?');
+		return $qb;
+	}
+
+	/**
+	 * Test that loadConfig retries without type/lazy columns on InvalidFieldNameException.
+	 */
+	public function testLoadConfigFallsBackOnMissingColumns(): void {
+		$exception = $this->createInvalidFieldNameException();
+
+		$successResult = $this->createMock(IResult::class);
+		$successResult->method('fetchAll')->willReturn([
+			['appid' => 'core', 'configkey' => 'vendor', 'configvalue' => 'owncloud'],
+			['appid' => 'core', 'configkey' => 'installedat', 'configvalue' => '1234567890'],
+		]);
+
+		$qb = $this->createMockQueryBuilder();
+		// First call throws (columns missing), second call succeeds (fallback query)
+		$qb->method('executeQuery')
+			->willReturnOnConsecutiveCalls(
+				$this->throwException($exception),
+				$successResult,
+			);
+
+		$this->connection->method('getQueryBuilder')->willReturn($qb);
+
+		$appConfig = $this->getAppConfig();
+
+		// getValueString triggers loadConfig internally
+		$value = $appConfig->getValueString('core', 'vendor');
+		$this->assertSame('owncloud', $value);
+	}
+
+	/**
+	 * Test that non-INVALID_FIELD_NAME exceptions are re-thrown, not swallowed.
+	 */
+	public function testLoadConfigRethrowsOtherExceptions(): void {
+		$driverException = $this->createMock(\Doctrine\DBAL\Driver\Exception::class);
+		$dbalException = new \Doctrine\DBAL\Exception\SyntaxErrorException($driverException, null);
+		$exception = DbalException::wrap($dbalException);
+
+		$qb = $this->createMockQueryBuilder();
+		$qb->method('executeQuery')->willThrowException($exception);
+
+		$this->connection->method('getQueryBuilder')->willReturn($qb);
+
+		$appConfig = $this->getAppConfig();
+
+		$this->expectException(DBException::class);
+		$appConfig->getValueString('core', 'vendor');
+	}
+
+	/**
+	 * Test that insert omits lazy/type columns when migration is not completed.
+	 */
+	public function testInsertOmitsNewColumnsInFallbackMode(): void {
+		$exception = $this->createInvalidFieldNameException();
+
+		$loadResult = $this->createMock(IResult::class);
+		$loadResult->method('fetchAll')->willReturn([]);
+
+		$qb = $this->createMockQueryBuilder();
+
+		$callCount = 0;
+		$qb->method('executeQuery')
+			->willReturnCallback(function () use ($exception, $loadResult, &$callCount) {
+				$callCount++;
+				if ($callCount === 1) {
+					throw $exception;
+				}
+				return $loadResult;
+			});
+
+		// Verify insert() is called (meaning we reached the insert path)
+		$qb->expects(self::once())->method('insert')->with('appconfig')->willReturn($qb);
+		$qb->method('executeStatement')->willReturn(1);
+
+		// Track which columns are set via setValue
+		$setColumns = [];
+		$qb->method('setValue')
+			->willReturnCallback(function (string $column) use ($qb, &$setColumns) {
+				$setColumns[] = $column;
+				return $qb;
+			});
+
+		$this->connection->method('getQueryBuilder')->willReturn($qb);
+
+		$appConfig = $this->getAppConfig();
+		$appConfig->setValueString('core', 'vendor', 'owncloud');
+
+		$this->assertContains('appid', $setColumns);
+		$this->assertContains('configkey', $setColumns);
+		$this->assertContains('configvalue', $setColumns);
+		$this->assertNotContains('lazy', $setColumns, 'lazy column should be omitted in fallback mode');
+		$this->assertNotContains('type', $setColumns, 'type column should be omitted in fallback mode');
+	}
+}

tests/lib/Config/UserConfigMigrationFallbackTest.php

@@ -0,0 +1,180 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace Test\lib\Config;
+
+use Doctrine\DBAL\Exception\InvalidFieldNameException;
+use OC\Config\ConfigManager;
+use OC\Config\PresetManager;
+use OC\Config\UserConfig;
+use OC\DB\Exceptions\DbalException;
+use OCP\DB\Exception as DBException;
+use OCP\DB\IResult;
+use OCP\DB\QueryBuilder\IExpressionBuilder;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\EventDispatcher\IEventDispatcher;
+use OCP\IConfig;
+use OCP\IDBConnection;
+use OCP\Security\ICrypto;
+use PHPUnit\Framework\MockObject\MockObject;
+use Psr\Log\LoggerInterface;
+use Test\TestCase;
+
+/**
+ * Tests the ownCloud migration fallback in UserConfig.
+ *
+ * When migrating from ownCloud, the preferences table lacks 'type', 'lazy',
+ * 'flags', and 'indexed' columns. UserConfig::loadConfig() must catch the
+ * resulting DBException and retry with a query that only selects columns
+ * present in ownCloud's schema.
+ */
+class UserConfigMigrationFallbackTest extends TestCase {
+	private IDBConnection&MockObject $connection;
+	private IConfig&MockObject $config;
+	private ConfigManager&MockObject $configManager;
+	private PresetManager&MockObject $presetManager;
+	private LoggerInterface&MockObject $logger;
+	private ICrypto&MockObject $crypto;
+	private IEventDispatcher&MockObject $dispatcher;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->connection = $this->createMock(IDBConnection::class);
+		$this->config = $this->createMock(IConfig::class);
+		$this->configManager = $this->createMock(ConfigManager::class);
+		$this->presetManager = $this->createMock(PresetManager::class);
+		$this->logger = $this->createMock(LoggerInterface::class);
+		$this->crypto = $this->createMock(ICrypto::class);
+		$this->dispatcher = $this->createMock(IEventDispatcher::class);
+	}
+
+	private function getUserConfig(): UserConfig {
+		return new UserConfig(
+			$this->connection,
+			$this->config,
+			$this->configManager,
+			$this->presetManager,
+			$this->logger,
+			$this->crypto,
+			$this->dispatcher,
+		);
+	}
+
+	private function createInvalidFieldNameException(): DBException {
+		$driverException = $this->createMock(\Doctrine\DBAL\Driver\Exception::class);
+		$dbalException = new InvalidFieldNameException($driverException, null);
+		return DbalException::wrap($dbalException);
+	}
+
+	private function createMockQueryBuilder(): IQueryBuilder&MockObject {
+		$expression = $this->createMock(IExpressionBuilder::class);
+		$qb = $this->createMock(IQueryBuilder::class);
+		$qb->method('from')->willReturn($qb);
+		$qb->method('select')->willReturn($qb);
+		$qb->method('addSelect')->willReturn($qb);
+		$qb->method('where')->willReturn($qb);
+		$qb->method('andWhere')->willReturn($qb);
+		$qb->method('set')->willReturn($qb);
+		$qb->method('expr')->willReturn($expression);
+		$qb->method('insert')->willReturn($qb);
+		$qb->method('setValue')->willReturn($qb);
+		$qb->method('createNamedParameter')->willReturn('?');
+		return $qb;
+	}
+
+	/**
+	 * Test that loadConfig retries without new columns on InvalidFieldNameException.
+	 */
+	public function testLoadConfigFallsBackOnMissingColumns(): void {
+		$exception = $this->createInvalidFieldNameException();
+
+		$successResult = $this->createMock(IResult::class);
+		$successResult->method('fetchAll')->willReturn([
+			['appid' => 'settings', 'configkey' => 'email', 'configvalue' => 'user@example.com'],
+		]);
+
+		$qb = $this->createMockQueryBuilder();
+		$qb->method('executeQuery')
+			->willReturnOnConsecutiveCalls(
+				$this->throwException($exception),
+				$successResult,
+			);
+
+		$this->connection->method('getQueryBuilder')->willReturn($qb);
+
+		$userConfig = $this->getUserConfig();
+
+		$value = $userConfig->getValueString('user1', 'settings', 'email');
+		$this->assertSame('user@example.com', $value);
+	}
+
+	/**
+	 * Test that non-INVALID_FIELD_NAME exceptions are re-thrown.
+	 */
+	public function testLoadConfigRethrowsOtherExceptions(): void {
+		$driverException = $this->createMock(\Doctrine\DBAL\Driver\Exception::class);
+		$dbalException = new \Doctrine\DBAL\Exception\SyntaxErrorException($driverException, null);
+		$exception = DbalException::wrap($dbalException);
+
+		$qb = $this->createMockQueryBuilder();
+		$qb->method('executeQuery')->willThrowException($exception);
+
+		$this->connection->method('getQueryBuilder')->willReturn($qb);
+
+		$userConfig = $this->getUserConfig();
+
+		$this->expectException(DBException::class);
+		$userConfig->getValueString('user1', 'settings', 'email');
+	}
+
+	/**
+	 * Test that insert omits new columns when migration is not completed.
+	 */
+	public function testInsertOmitsNewColumnsInFallbackMode(): void {
+		$exception = $this->createInvalidFieldNameException();
+
+		$loadResult = $this->createMock(IResult::class);
+		$loadResult->method('fetchAll')->willReturn([]);
+
+		$qb = $this->createMockQueryBuilder();
+
+		$callCount = 0;
+		$qb->method('executeQuery')
+			->willReturnCallback(function () use ($exception, $loadResult, &$callCount) {
+				$callCount++;
+				if ($callCount === 1) {
+					throw $exception;
+				}
+				return $loadResult;
+			});
+
+		$qb->expects(self::once())->method('insert')->with('preferences')->willReturn($qb);
+		$qb->method('executeStatement')->willReturn(1);
+
+		$setColumns = [];
+		$qb->method('setValue')
+			->willReturnCallback(function (string $column) use ($qb, &$setColumns) {
+				$setColumns[] = $column;
+				return $qb;
+			});
+
+		$this->connection->method('getQueryBuilder')->willReturn($qb);
+
+		$userConfig = $this->getUserConfig();
+		$userConfig->setValueString('user1', 'settings', 'email', 'user@example.com');
+
+		$this->assertContains('userid', $setColumns);
+		$this->assertContains('appid', $setColumns);
+		$this->assertContains('configkey', $setColumns);
+		$this->assertContains('configvalue', $setColumns);
+		$this->assertNotContains('lazy', $setColumns, 'lazy column should be omitted in fallback mode');
+		$this->assertNotContains('type', $setColumns, 'type column should be omitted in fallback mode');
+		$this->assertNotContains('flags', $setColumns, 'flags column should be omitted in fallback mode');
+		$this->assertNotContains('indexed', $setColumns, 'indexed column should be omitted in fallback mode');
+	}
+}