From f90a187a159565f782ed3c22a68332c93718c245 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20M=C3=BCller?=
 <1005065+DeepDiver1975@users.noreply.github.com>
Date: Sun, 21 Jun 2026 23:11:54 +0200
Subject: [PATCH] fix(backgroundjob): don't log ERROR for stale job rows of
 removed apps
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JobList::buildJob() logged a full ERROR-level stack trace via
logException() whenever a job row referenced a class that no longer
exists — e.g. a stale oc_jobs row left behind by a removed or disabled
app (the "SyncJob does not exist" spam in issue #35589). The job was
already correctly skipped (return null), but the noisy ERROR log
recurred on every cron run for a benign, expected condition.

Check class_exists() first: a class that exists but fails to resolve as
a service is a genuine, actionable DI failure and still logs at ERROR via
logException(); a class that no longer exists (stale row) is now logged
once at DEBUG and skipped. Control flow and return values are unchanged.

Updates the existing JobListTest case accordingly: a missing-class job
must not call logException and instead logs at debug.

Fixes #35589

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Thomas Müller <1005065+DeepDiver1975@users.noreply.github.com>
---
 lib/private/BackgroundJob/JobList.php   | 13 +++++++++++--
 tests/lib/BackgroundJob/JobListTest.php | 10 ++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/lib/private/BackgroundJob/JobList.php b/lib/private/BackgroundJob/JobList.php
index e37b1db0ba70..a759632685ee 100644
--- a/lib/private/BackgroundJob/JobList.php
+++ b/lib/private/BackgroundJob/JobList.php
@@ -281,12 +281,21 @@ private function buildJob($row) {
 				/** @var IJob $job */
 				$job = \OC::$server->query($row['class']);
 			} catch (QueryException $e) {
-				$this->logger->logException($e, ['app' => 'core']);
 				if (\class_exists($row['class'])) {
+					// The class exists but could not be resolved as a service:
+					// this is a genuine, actionable DI failure -> log at ERROR.
+					$this->logger->logException($e, ['app' => 'core']);
 					$class = $row['class'];
 					$job = new $class();
 				} else {
-					// job from disabled app or old version of an app, no need to do anything
+					// The class does not exist anymore (stale job row from a
+					// disabled/removed app or an old version). This is a benign,
+					// expected condition, so only log it at DEBUG instead of
+					// spamming an ERROR-level stack trace on every cron run.
+					$this->logger->debug(
+						'Background job class ' . $row['class'] . ' does not exist (stale job row), skipping',
+						['app' => 'core']
+					);
 					return null;
 				}
 			}
diff --git a/tests/lib/BackgroundJob/JobListTest.php b/tests/lib/BackgroundJob/JobListTest.php
index 8ab6b24a23ba..2f88b2c021b0 100644
--- a/tests/lib/BackgroundJob/JobListTest.php
+++ b/tests/lib/BackgroundJob/JobListTest.php
@@ -285,9 +285,15 @@ private function addWrongJob() {
 		$query->execute();
 	}
 
-	public function testUnknownJobLogsException() {
+	public function testUnknownJobDoesNotLogException() {
+		// A stale job row whose class no longer exists must NOT be logged at
+		// ERROR level via logException (see issue #35589). It is a benign,
+		// expected condition and is only logged at DEBUG instead.
 		$this->addWrongJob();
-		$this->logger->expects($this->once())->method('logException');
+		$this->logger->expects($this->never())->method('logException');
+		$this->logger->expects($this->atLeastOnce())
+			->method('debug')
+			->with($this->stringContains('wrong job title'), ['app' => 'core']);
 		$this->instance->listJobs(function () {
 		});
 		$this->clearJobsList();