diff --git a/lib/private/App/AppStore/Fetcher/AppFetcher.php b/lib/private/App/AppStore/Fetcher/AppFetcher.php
index bbf4b00245b33..c14a6228ca38e 100644
--- a/lib/private/App/AppStore/Fetcher/AppFetcher.php
+++ b/lib/private/App/AppStore/Fetcher/AppFetcher.php
@@ -60,80 +60,95 @@ protected function fetch($ETag, $content, $allowUnstable = false) {
 			return [];
 		}
 
-		$allowPreReleases = $allowUnstable || $this->getChannel() === 'beta' || $this->getChannel() === 'daily' || $this->getChannel() === 'git';
-		$allowNightly = $allowUnstable || $this->getChannel() === 'daily' || $this->getChannel() === 'git';
+		$channel = $this->getChannel();
+		$allowPreReleases = $allowUnstable || $channel === 'beta' || $channel === 'daily' || $channel === 'git';
+		$allowNightly = $allowUnstable || $channel === 'daily' || $channel === 'git';
+
+		$versionParser = new VersionParser();
+		$ncVersion = $this->getVersion();
+		$currentPhpVersion = PHP_VERSION;
+		$ignoreMaxVersion = $this->ignoreMaxVersion;
+
+		/** @var array<string, array{0: string, 1: string}> $platformSpecCache */
+		$platformSpecCache = [];
+		/** @var array<string, array{0: string, 1: string}> $phpSpecCache */
+		$phpSpecCache = [];
 
 		foreach ($response['data'] as $dataKey => $app) {
-			$releases = [];
+			$bestRelease = null;
 
-			// Filter all compatible releases
+			// Filter compatible releases
 			foreach ($app['releases'] as $release) {
-				// Exclude all nightly and pre-releases if required
-				if (($allowNightly || $release['isNightly'] === false)
-					&& ($allowPreReleases || !str_contains($release['version'], '-'))) {
-					// Exclude all versions not compatible with the current version
-					try {
-						$versionParser = new VersionParser();
-						$serverVersion = $versionParser->getVersion($release['rawPlatformVersionSpec']);
-						$ncVersion = $this->getVersion();
-						$minServerVersion = $serverVersion->getMinimumVersion();
-						$maxServerVersion = $serverVersion->getMaximumVersion();
-						$minFulfilled = $this->compareVersion->isCompatible($ncVersion, $minServerVersion, '>=');
-						$maxFulfilled = $maxServerVersion !== ''
-							&& $this->compareVersion->isCompatible($ncVersion, $maxServerVersion, '<=');
-						$isPhpCompatible = true;
-						if (($release['rawPhpVersionSpec'] ?? '*') !== '*') {
-							$phpVersion = $versionParser->getVersion($release['rawPhpVersionSpec']);
-							$minPhpVersion = $phpVersion->getMinimumVersion();
-							$maxPhpVersion = $phpVersion->getMaximumVersion();
-							$minPhpFulfilled = $minPhpVersion === '' || $this->compareVersion->isCompatible(
-								PHP_VERSION,
-								$minPhpVersion,
-								'>='
-							);
-							$maxPhpFulfilled = $maxPhpVersion === '' || $this->compareVersion->isCompatible(
-								PHP_VERSION,
-								$maxPhpVersion,
-								'<='
-							);
-
-							$isPhpCompatible = $minPhpFulfilled && $maxPhpFulfilled;
-						}
-						if ($minFulfilled && ($this->ignoreMaxVersion || $maxFulfilled) && $isPhpCompatible) {
-							$releases[] = $release;
+				// Exclude nightly builds
+				if ($release['isNightly'] !== false && !$allowNightly) {
+					continue;
+				}
+
+				// Exclude pre-releases
+				if (str_contains($release['version'], '-') && !$allowPreReleases) {
+					continue;
+				}
+
+				try {
+					$rawPlatformVersionSpec = $release['rawPlatformVersionSpec'] ?? null;
+					if ($rawPlatformVersionSpec === null) {
+						continue; // no spec; treat as incompatible, skip
+					}
+					if (!isset($platformSpecCache[$rawPlatformVersionSpec])) {
+						$serverVersion = $versionParser->getVersion($rawPlatformVersionSpec);
+						$platformSpecCache[$rawPlatformVersionSpec] = [
+							$serverVersion->getMinimumVersion(),
+							$serverVersion->getMaximumVersion(),
+						];
+					}
+
+					[$minServerVersion, $maxServerVersion] = $platformSpecCache[$rawPlatformVersionSpec];
+
+					$minFulfilled = $this->compareVersion->isCompatible($ncVersion, $minServerVersion, '>=');
+					$maxFulfilled = $maxServerVersion !== '' && $this->compareVersion->isCompatible($ncVersion, $maxServerVersion, '<=');
+
+					$isPhpCompatible = true;
+
+					$rawPhpVersionSpec = $release['rawPhpVersionSpec'] ?? '*';
+					if ($rawPhpVersionSpec !== '*') {
+						if (!isset($phpSpecCache[$rawPhpVersionSpec])) {
+							$phpVersion = $versionParser->getVersion($rawPhpVersionSpec);
+							$phpSpecCache[$rawPhpVersionSpec] = [
+								$phpVersion->getMinimumVersion(),
+								$phpVersion->getMaximumVersion(),
+							];
 						}
-					} catch (\InvalidArgumentException $e) {
-						$this->logger->warning($e->getMessage(), [
-							'exception' => $e,
-						]);
+		
+						[$minPhpVersion, $maxPhpVersion] = $phpSpecCache[$rawPhpVersionSpec];
+
+						$minPhpFulfilled = $minPhpVersion === '' || $this->compareVersion->isCompatible($currentPhpVersion, $minPhpVersion, '>=');
+						$maxPhpFulfilled = $maxPhpVersion === '' || $this->compareVersion->isCompatible($currentPhpVersion, $maxPhpVersion, '<=');
+						
+						$isPhpCompatible = $minPhpFulfilled && $maxPhpFulfilled;
+					}
+
+					$isCompatible = $minFulfilled && ($ignoreMaxVersion || $maxFulfilled) && $isPhpCompatible;
+
+					if (!$isCompatible) {
+						continue;
 					}
+
+					$betterRelease = $bestRelease === null || version_compare((string)$release['version'], (string)$bestRelease['version'], '>');
+					if ($betterRelease) {
+						$bestRelease = $release;
+					}
+				} catch (\InvalidArgumentException $e) {
+					$this->logger->warning($e->getMessage(), [ 'exception' => $e, ]);
 				}
 			}
 
-			if (empty($releases)) {
+			if ($bestRelease === null) {
 				// Remove apps that don't have a matching release
 				$response['data'][$dataKey] = [];
 				continue;
 			}
 
-			// Get the highest version
-			$versions = [];
-			foreach ($releases as $release) {
-				$versions[] = $release['version'];
-			}
-			usort($versions, function ($version1, $version2) {
-				return version_compare($version1, $version2);
-			});
-			$versions = array_reverse($versions);
-			if (isset($versions[0])) {
-				$highestVersion = $versions[0];
-				foreach ($releases as $release) {
-					if ((string)$release['version'] === (string)$highestVersion) {
-						$response['data'][$dataKey]['releases'] = [$release];
-						break;
-					}
-				}
-			}
+			$response['data'][$dataKey]['releases'] = [$bestRelease];
 		}
 
 		$response['data'] = array_values(array_filter($response['data']));
@@ -158,12 +173,13 @@ public function get($allowUnstable = false): array {
 		if (empty($apps)) {
 			return [];
 		}
-		$allowList = $this->config->getSystemValue('appsallowlist');
 
 		// If the admin specified a allow list, filter apps from the appstore
+		$allowList = $this->config->getSystemValue('appsallowlist');
 		if (is_array($allowList) && $this->registry->delegateHasValidSubscription()) {
-			return array_filter($apps, function ($app) use ($allowList) {
-				return in_array($app['id'], $allowList);
+			$allowSet = array_flip($allowList);
+			return array_filter($apps, static function ($app) use ($allowSet) {
+				return isset($allowSet[$app['id']]);
 			});
 		}
 
diff --git a/lib/private/App/AppStore/Fetcher/Fetcher.php b/lib/private/App/AppStore/Fetcher/Fetcher.php
index 3304b414ad747..d1f61748f70fe 100644
--- a/lib/private/App/AppStore/Fetcher/Fetcher.php
+++ b/lib/private/App/AppStore/Fetcher/Fetcher.php
@@ -134,6 +134,7 @@ public function get($allowUnstable = false) {
 
 		$ETag = '';
 		$content = '';
+		$cachedData = null;
 
 		try {
 			// File does already exists
@@ -141,6 +142,10 @@ public function get($allowUnstable = false) {
 			$jsonBlob = json_decode($file->getContent(), true);
 
 			if (is_array($jsonBlob)) {
+				if (isset($jsonBlob['data']) && is_array($jsonBlob['data'])) {
+					$cachedData = $jsonBlob['data'];
+				}
+
 				// No caching when the version has been updated
 				if (isset($jsonBlob['ncversion']) && $jsonBlob['ncversion'] === $this->getVersion()) {
 					// If the timestamp is older than 3600 seconds request the files new
@@ -170,20 +175,17 @@ public function get($allowUnstable = false) {
 			$responseJson = $this->fetch($ETag, $content, $allowUnstable);
 
 			if (empty($responseJson) || empty($responseJson['data'])) {
-				return [];
+				return is_array($cachedData) ? $cachedData : [];
 			}
 
 			$file->putContent(json_encode($responseJson));
-			return json_decode($file->getContent(), true)['data'];
+			return $responseJson['data'];
 		} catch (ConnectException $e) {
 			$this->logger->warning('Could not connect to appstore: ' . $e->getMessage(), ['app' => 'appstoreFetcher']);
-			return [];
+			return is_array($cachedData) ? $cachedData : [];
 		} catch (\Exception $e) {
-			$this->logger->warning($e->getMessage(), [
-				'exception' => $e,
-				'app' => 'appstoreFetcher',
-			]);
-			return [];
+			$this->logger->warning($e->getMessage(), ['exception' => $e, 'app' => 'appstoreFetcher',]);
+			return is_array($cachedData) ? $cachedData : [];
 		}
 	}
 
diff --git a/tests/lib/App/AppStore/Fetcher/AppFetcherTest.php b/tests/lib/App/AppStore/Fetcher/AppFetcherTest.php
index c6f0df7d2fb6f..34f58621f2661 100644
--- a/tests/lib/App/AppStore/Fetcher/AppFetcherTest.php
+++ b/tests/lib/App/AppStore/Fetcher/AppFetcherTest.php
@@ -2250,4 +2250,97 @@ public function testGetAppsAllowlistCustomAppstore(): void {
 		$this->assertEquals(count($apps), 1);
 		$this->assertEquals($apps[0]['id'], 'contacts');
 	}
+
+	public function testGetKeepsHighestCompatibleReleaseOnly(): void {
+		$this->config->method('getSystemValueString')
+			->willReturnCallback(function ($key, $default) {
+				if ($key === 'version') {
+					return '30.0.0';
+				} elseif ($key === 'appstoreurl' && $default === 'https://apps.nextcloud.com/api/v1') {
+					return 'https://custom.appsstore.endpoint/api/v1';
+				}
+				return $default;
+			});
+		$this->config->method('getSystemValueBool')
+			->willReturnArgument(1);
+
+		$file = $this->createMock(ISimpleFile::class);
+		$folder = $this->createMock(ISimpleFolder::class);
+		$folder
+			->expects($this->once())
+			->method('getFile')
+			->with('apps.json')
+			->willThrowException(new NotFoundException());
+		$folder
+			->expects($this->once())
+			->method('newFile')
+			->with('apps.json')
+			->willReturn($file);
+		$this->appData
+			->expects($this->once())
+			->method('getFolder')
+			->with('/')
+			->willReturn($folder);
+
+		$client = $this->createMock(IClient::class);
+		$this->clientService
+			->expects($this->once())
+			->method('newClient')
+			->willReturn($client);
+
+		$response = $this->createMock(IResponse::class);
+		$client
+			->expects($this->once())
+			->method('get')
+			->with('https://custom.appsstore.endpoint/api/v1/apps.json')
+			->willReturn($response);
+
+		$response
+			->expects($this->once())
+			->method('getBody')
+			->willReturn(json_encode([
+				[
+					'id' => 'testapp',
+					'releases' => [
+						[
+							'version' => '1.0.0',
+							'isNightly' => false,
+							'rawPhpVersionSpec' => '*',
+							'rawPlatformVersionSpec' => '>=30 <=30',
+						],
+						[
+							'version' => '1.5.0',
+							'isNightly' => false,
+							'rawPhpVersionSpec' => '*',
+							'rawPlatformVersionSpec' => '>=30 <=30',
+						],
+						[
+							'version' => '2.0.0',
+							'isNightly' => false,
+							'rawPhpVersionSpec' => '*',
+							'rawPlatformVersionSpec' => '>=31 <=31',
+						],
+					],
+				],
+			], JSON_THROW_ON_ERROR));
+		$response->method('getHeader')
+			->with($this->equalTo('ETag'))
+			->willReturn('"myETag"');
+
+		$this->timeFactory
+			->expects($this->once())
+			->method('getTime')
+			->willReturn(1234);
+
+		$file
+			->expects($this->once())
+			->method('putContent');
+
+		$result = $this->fetcher->get();
+
+		$this->assertCount(1, $result);
+		$this->assertSame('testapp', $result[0]['id']);
+		$this->assertCount(1, $result[0]['releases']);
+		$this->assertSame('1.5.0', $result[0]['releases'][0]['version']);
+	}
 }
diff --git a/tests/lib/App/AppStore/Fetcher/FetcherBase.php b/tests/lib/App/AppStore/Fetcher/FetcherBase.php
index 4784e76d574f6..66f972198538f 100644
--- a/tests/lib/App/AppStore/Fetcher/FetcherBase.php
+++ b/tests/lib/App/AppStore/Fetcher/FetcherBase.php
@@ -149,9 +149,8 @@ public function testGetWithNotExistingFileAndUpToDateTimestampAndVersion(): void
 			->method('putContent')
 			->with($fileData);
 		$file
-			->expects($this->once())
-			->method('getContent')
-			->willReturn($fileData);
+			->expects($this->never())
+			->method('getContent');
 		$this->timeFactory
 			->expects($this->once())
 			->method('getTime')
@@ -199,12 +198,9 @@ public function testGetWithAlreadyExistingFileAndOutdatedTimestamp(): void {
 			->method('putContent')
 			->with($fileData);
 		$file
-			->expects($this->exactly(2))
+			->expects($this->once())
 			->method('getContent')
-			->willReturnOnConsecutiveCalls(
-				'{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}},"ncversion":"11.0.0.2"}',
-				$fileData
-			);
+			->willReturn('{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}},"ncversion":"11.0.0.2"}');
 		$this->timeFactory
 			->expects($this->exactly(2))
 			->method('getTime')
@@ -275,12 +271,9 @@ public function testGetWithAlreadyExistingFileAndNoVersion(): void {
 			->method('putContent')
 			->with($fileData);
 		$file
-			->expects($this->exactly(2))
+			->expects($this->once())
 			->method('getContent')
-			->willReturnOnConsecutiveCalls(
-				'{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}}',
-				$fileData
-			);
+			->willReturn('{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}}');
 		$this->timeFactory
 			->expects($this->once())
 			->method('getTime')
@@ -348,12 +341,9 @@ public function testGetWithAlreadyExistingFileAndOutdatedVersion(): void {
 			->method('putContent')
 			->with($fileData);
 		$file
-			->expects($this->exactly(2))
+			->expects($this->once())
 			->method('getContent')
-			->willReturnOnConsecutiveCalls(
-				'{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}},"ncversion":"11.0.0.1"',
-				$fileData
-			);
+			->willReturn('{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}},"ncversion":"11.0.0.1"');
 		$this->timeFactory
 			->method('getTime')
 			->willReturn(1201);
@@ -388,12 +378,75 @@ public function testGetWithAlreadyExistingFileAndOutdatedVersion(): void {
 		$this->assertSame($expected, $this->fetcher->get());
 	}
 
-	public function testGetWithExceptionInClient(): void {
+	public function testGetWithExceptionInClientReturnsStaleCachedData(): void {
 		$this->config->method('getSystemValueString')
+			->willReturnCallback(function ($key, $default) {
+				if ($key === 'version') {
+					return '11.0.0.2';
+				}
+				return $default;
+			});
+		$this->config->method('getSystemValueBool')
 			->willReturnArgument(1);
+
+		$folder = $this->createMock(ISimpleFolder::class);
+		$file = $this->createMock(ISimpleFile::class);
+		$this->appData
+			->expects($this->once())
+			->method('getFolder')
+			->with('/')
+			->willReturn($folder);
+		$folder
+			->expects($this->once())
+			->method('getFile')
+			->with($this->fileName)
+			->willReturn($file);
+		$file
+			->expects($this->once())
+			->method('getContent')
+			->willReturn('{"timestamp":1200,"data":[{"id":"MyApp"}],"ncversion":"11.0.0.2","ETag":"\"myETag\""}');
+
+		$this->timeFactory
+			->expects($this->once())
+			->method('getTime')
+			->willReturn(4801);
+
+		$client = $this->createMock(IClient::class);
+		$this->clientService
+			->expects($this->once())
+			->method('newClient')
+			->willReturn($client);
+		$client
+			->expects($this->once())
+			->method('get')
+			->with($this->endpoint)
+			->willThrowException(new \Exception('refresh failed'));
+
+		$expected = [
+			[
+				'id' => 'MyApp',
+			],
+		];
+
+		$this->assertSame($expected, $this->fetcher->get());
+	}
+
+	public function testGetReturnsStaleCachedDataWhenRefreshReturnsEmptyResult(): void {
+		$this->config->method('getSystemValueString')
+			->willReturnCallback(function ($key, $default) {
+				if ($key === 'version') {
+					return '11.0.0.2';
+				}
+				return $default;
+			});
 		$this->config->method('getSystemValueBool')
 			->willReturnArgument(1);
 
+		$this->config->method('getAppValue')
+			->willReturnMap([
+				['settings', 'appstore-fetcher-lastFailure', '0', '4800'],
+			]);
+
 		$folder = $this->createMock(ISimpleFolder::class);
 		$file = $this->createMock(ISimpleFile::class);
 		$this->appData
@@ -409,19 +462,102 @@ public function testGetWithExceptionInClient(): void {
 		$file
 			->expects($this->once())
 			->method('getContent')
-			->willReturn('{"timestamp":1200,"data":{"MyApp":{"id":"MyApp"}}}');
+			->willReturn('{"timestamp":1200,"data":[{"id":"MyApp"}],"ncversion":"11.0.0.2","ETag":"\"myETag\""}');
+
+		$this->timeFactory
+			->expects($this->exactly(2))
+			->method('getTime')
+			->willReturnOnConsecutiveCalls(4801, 4801);
+
+		$expected = [
+			[
+				'id' => 'MyApp',
+			],
+		];
+
+		$this->assertSame($expected, $this->fetcher->get());
+	}
+
+	public function testGetReturnsFreshDataWithoutReadingBackWrittenCache(): void {
+		$this->config
+			->method('getSystemValueString')
+			->willReturnCallback(function ($var, $default) {
+				if ($var === 'appstoreurl') {
+					return 'https://apps.nextcloud.com/api/v1';
+				} elseif ($var === 'version') {
+					return '11.0.0.2';
+				}
+				return $default;
+			});
+		$this->config->method('getSystemValueBool')
+			->willReturnArgument(1);
+
+		$folder = $this->createMock(ISimpleFolder::class);
+		$file = $this->createMock(ISimpleFile::class);
+		$this->appData
+			->expects($this->once())
+			->method('getFolder')
+			->with('/')
+			->willReturn($folder);
+		$folder
+			->expects($this->once())
+			->method('getFile')
+			->with($this->fileName)
+			->willThrowException(new NotFoundException());
+		$folder
+			->expects($this->once())
+			->method('newFile')
+			->with($this->fileName)
+			->willReturn($file);
+
 		$client = $this->createMock(IClient::class);
 		$this->clientService
 			->expects($this->once())
 			->method('newClient')
 			->willReturn($client);
+
+		$response = $this->createMock(IResponse::class);
 		$client
 			->expects($this->once())
 			->method('get')
 			->with($this->endpoint)
-			->willThrowException(new \Exception());
+			->willReturn($response);
+
+		$response
+			->expects($this->once())
+			->method('getBody')
+			->willReturn('[{"id":"MyNewApp","foo":"foo"},{"id":"bar"}]');
+		$response
+			->method('getHeader')
+			->with($this->equalTo('ETag'))
+			->willReturn('"myETag"');
+
+		$fileData = '{"data":[{"id":"MyNewApp","foo":"foo"},{"id":"bar"}],"timestamp":1502,"ncversion":"11.0.0.2","ETag":"\"myETag\""}';
+		$file
+			->expects($this->once())
+			->method('putContent')
+			->with($fileData);
 
-		$this->assertSame([], $this->fetcher->get());
+		$file
+			->expects($this->never())
+			->method('getContent');
+
+		$this->timeFactory
+			->expects($this->once())
+			->method('getTime')
+			->willReturn(1502);
+
+		$expected = [
+			[
+				'id' => 'MyNewApp',
+				'foo' => 'foo',
+			],
+			[
+				'id' => 'bar',
+			],
+		];
+
+		$this->assertSame($expected, $this->fetcher->get());
 	}
 
 	public function testGetMatchingETag(): void {
@@ -462,12 +598,9 @@ public function testGetMatchingETag(): void {
 			->method('putContent')
 			->with($newData);
 		$file
-			->expects($this->exactly(2))
+			->expects($this->once())
 			->method('getContent')
-			->willReturnOnConsecutiveCalls(
-				$origData,
-				$newData,
-			);
+			->willReturn($origData);
 		$this->timeFactory
 			->expects($this->exactly(2))
 			->method('getTime')
@@ -545,12 +678,9 @@ public function testGetNoMatchingETag(): void {
 			->method('putContent')
 			->with($fileData);
 		$file
-			->expects($this->exactly(2))
+			->expects($this->once())
 			->method('getContent')
-			->willReturnOnConsecutiveCalls(
-				'{"data":[{"id":"MyOldApp","abc":"def"}],"timestamp":1200,"ncversion":"11.0.0.2","ETag":"\"myETag\""}',
-				$fileData,
-			);
+			->willReturn('{"data":[{"id":"MyOldApp","abc":"def"}],"timestamp":1200,"ncversion":"11.0.0.2","ETag":"\"myETag\""}');
 		$this->timeFactory
 			->expects($this->exactly(2))
 			->method('getTime')
@@ -636,12 +766,9 @@ public function testFetchAfterUpgradeNoETag(): void {
 			->method('putContent')
 			->with($fileData);
 		$file
-			->expects($this->exactly(2))
+			->expects($this->once())
 			->method('getContent')
-			->willReturnOnConsecutiveCalls(
-				'{"data":[{"id":"MyOldApp","abc":"def"}],"timestamp":1200,"ncversion":"11.0.0.2","ETag":"\"myETag\""}',
-				$fileData
-			);
+			->willReturn('{"data":[{"id":"MyOldApp","abc":"def"}],"timestamp":1200,"ncversion":"11.0.0.2","ETag":"\"myETag\""}');
 		$client = $this->createMock(IClient::class);
 		$this->clientService
 			->expects($this->once())