diff --git a/packages/vitec/Classes/Command/ClientErrorCleanupCommand.php b/packages/vitec/Classes/Command/ClientErrorCleanupCommand.php
new file mode 100644
index 0000000..f8e6f38
--- /dev/null
+++ b/packages/vitec/Classes/Command/ClientErrorCleanupCommand.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Evomedien\Vitec\Command;
+
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use TYPO3\CMS\Core\Database\ConnectionPool;
+
+#[AsCommand(
+    name: 'vitec:client-error-cleanup',
+    description: 'Delete client error reports (tx_vitec_clienterrorlog) older than 30 days; run daily via cron',
+)]
+final class ClientErrorCleanupCommand extends Command
+{
+    private const TABLE = 'tx_vitec_clienterrorlog';
+    private const DEFAULT_DAYS = 30;
+
+    public function __construct(private readonly ConnectionPool $connectionPool)
+    {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        $this->addOption('days', 'd', InputOption::VALUE_REQUIRED, 'Keep entries younger than this many days', (string)self::DEFAULT_DAYS);
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $days = (int)$input->getOption('days');
+        if ($days < 1) {
+            $output->writeln('<error>--days must be at least 1</error>');
+            return Command::INVALID;
+        }
+        $cutoff = time() - $days * 86400;
+        $conn = $this->connectionPool->getConnectionForTable(self::TABLE);
+        $deleted = $conn->executeStatement('DELETE FROM ' . self::TABLE . ' WHERE crdate < ?', [$cutoff]);
+        $remaining = (int)$conn->executeQuery('SELECT COUNT(*) FROM ' . self::TABLE)->fetchOne();
+        $output->writeln(sprintf(
+            'deleted %d client error report(s) older than %d days (before %s), %d remaining',
+            $deleted,
+            $days,
+            date('Y-m-d H:i', $cutoff),
+            $remaining
+        ));
+        return Command::SUCCESS;
+    }
+}
diff --git a/packages/vitec/Classes/Controller/Backend/SsrController.php b/packages/vitec/Classes/Controller/Backend/SsrController.php
index 485ba42..3c8ff6c 100644
--- a/packages/vitec/Classes/Controller/Backend/SsrController.php
+++ b/packages/vitec/Classes/Controller/Backend/SsrController.php
@@ -11,6 +11,7 @@ use TYPO3\CMS\Backend\Attribute\AsController;
 use TYPO3\CMS\Backend\Routing\UriBuilder;
 use TYPO3\CMS\Backend\Template\ModuleTemplateFactory;
 use TYPO3\CMS\Core\Core\Environment;
+use TYPO3\CMS\Core\Database\Connection;
 use TYPO3\CMS\Core\Database\ConnectionPool;
 use TYPO3\CMS\Core\Http\JsonResponse;
 use TYPO3\CMS\Core\Http\RedirectResponse;
@@ -73,10 +74,51 @@ final class SsrController
             'healthError' => $healthError,
             'purgeLog' => $this->rows('tx_vitec_ssrpurgelog', 30),
             'healthLog' => $this->rows('tx_vitec_ssrhealthlog', 10),
+            'clientErrors' => $this->clientErrors(50),
+            'clientErrorCount24h' => $this->clientErrorCount24h(),
         ]);
         return $view->renderResponse('Ssr/Index');
     }
 
+    /**
+     * Client error reports of the last 24 hours (POST /api/vitec/client-error,
+     * ClientErrorMiddleware), newest first. Rows carry a "host" (URL without
+     * scheme/query) and a shortened user agent for the table; the full
+     * values stay in the row for the details toggle.
+     */
+    private function clientErrors(int $limit): array
+    {
+        try {
+            $qb = $this->connectionPool->getQueryBuilderForTable('tx_vitec_clienterrorlog');
+            $rows = $qb->select('*')->from('tx_vitec_clienterrorlog')
+                ->where($qb->expr()->gt('crdate', $qb->createNamedParameter(time() - 86400, Connection::PARAM_INT)))
+                ->orderBy('uid', 'DESC')->setMaxResults($limit)
+                ->executeQuery()->fetchAllAssociative();
+        } catch (\Throwable) {
+            return [];
+        }
+        foreach ($rows as &$row) {
+            $path = (string)(parse_url((string)$row['url'], PHP_URL_PATH) ?? '');
+            $row['path'] = $path !== '' ? $path : (string)$row['url'];
+            $ua = (string)$row['user_agent'];
+            $row['ua_short'] = mb_strlen($ua) > 60 ? mb_substr($ua, 0, 57) . '...' : $ua;
+            $row['is_chunk_reload'] = str_contains(strtolower((string)$row['message']), 'chunk reload');
+        }
+        unset($row);
+        return $rows;
+    }
+
+    private function clientErrorCount24h(): int
+    {
+        try {
+            return (int)$this->connectionPool->getConnectionForTable('tx_vitec_clienterrorlog')
+                ->executeQuery('SELECT COUNT(*) FROM tx_vitec_clienterrorlog WHERE crdate > ?', [time() - 86400])
+                ->fetchOne();
+        } catch (\Throwable) {
+            return 0;
+        }
+    }
+
     public function purgeAction(ServerRequestInterface $request): ResponseInterface
     {
         $body = (array)$request->getParsedBody();
diff --git a/packages/vitec/Classes/Middleware/ClientErrorMiddleware.php b/packages/vitec/Classes/Middleware/ClientErrorMiddleware.php
new file mode 100644
index 0000000..dcc2365
--- /dev/null
+++ b/packages/vitec/Classes/Middleware/ClientErrorMiddleware.php
@@ -0,0 +1,184 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Evomedien\Vitec\Middleware;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use TYPO3\CMS\Core\Database\ConnectionPool;
+use TYPO3\CMS\Core\Http\NormalizedParams;
+use TYPO3\CMS\Core\Http\Response;
+use TYPO3\CMS\Core\RateLimiter\RateLimiterFactory;
+
+/**
+ * Client error endpoint: POST /api/vitec/client-error
+ *
+ * The React frontend reports browser-side failures here (window.onerror,
+ * unhandledrejection, chunk reloads after a deploy, element error
+ * boundaries) - contract 0072-FE section 4, accepted in 0077-BE:
+ *
+ *   {url, message, stack, release, userAgent}  ->  204 No Content
+ *
+ * Guards, all answered with a 4xx and no body:
+ *   405  method other than POST
+ *   413  body larger than 8 KB (Content-Length or actual bytes)
+ *   400  not a JSON object, or "message" missing/empty
+ *   429  more than 30 reports per minute from one IP (sliding window
+ *        via TYPO3's rate limiter, cache "ratelimiter")
+ *
+ * Entries land in tx_vitec_clienterrorlog with the IP anonymized (IPv4
+ * last octet zeroed, IPv6 cut to /48); the full IP is only the key of
+ * the rate limiter and is never stored. No session, no cookies - a
+ * navigator.sendBeacon() call must get through unchanged. Rows older
+ * than 30 days are removed by vitec:client-error-cleanup.
+ */
+final class ClientErrorMiddleware implements MiddlewareInterface
+{
+    private const PATH = '/api/vitec/client-error';
+    private const MAX_BODY_BYTES = 8192;
+    private const LIMIT_PER_MINUTE = 30;
+    private const TABLE = 'tx_vitec_clienterrorlog';
+
+    public function __construct(
+        private readonly ConnectionPool $connectionPool,
+        private readonly RateLimiterFactory $rateLimiterFactory,
+    ) {}
+
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        $path = rtrim($request->getUri()->getPath(), '/');
+        if ($path !== self::PATH) {
+            return $handler->handle($request);
+        }
+
+        $method = strtoupper($request->getMethod());
+        if ($method === 'OPTIONS') {
+            return $this->empty(204)->withHeader('Allow', 'POST, OPTIONS');
+        }
+        if ($method !== 'POST') {
+            return $this->empty(405)->withHeader('Allow', 'POST, OPTIONS');
+        }
+
+        $declared = (int)$request->getHeaderLine('Content-Length');
+        if ($declared > self::MAX_BODY_BYTES) {
+            return $this->empty(413);
+        }
+
+        // Rate limit first, so a flood of oversized or broken bodies is
+        // cheap to refuse as well.
+        $ip = '';
+        try {
+            $normalized = $request->getAttribute('normalizedParams') ?? NormalizedParams::createFromRequest($request);
+            $ip = (string)$normalized->getRemoteAddress();
+            $limiter = $this->rateLimiterFactory->createLimiter([
+                'id' => 'vitec-client-error',
+                'policy' => 'sliding_window',
+                'limit' => self::LIMIT_PER_MINUTE,
+                'interval' => '1 minute',
+            ], $ip);
+            $limit = $limiter->consume(1);
+            if (!$limit->isAccepted()) {
+                $retry = max(1, $limit->getRetryAfter()->getTimestamp() - time());
+                return $this->empty(429)->withHeader('Retry-After', (string)$retry);
+            }
+        } catch (\Throwable) {
+            // A broken limiter must not take the endpoint down; the
+            // body limit and the 30-day cleanup still bound the damage.
+        }
+
+        $body = $request->getBody();
+        if ($body->isSeekable()) {
+            $body->rewind();
+        }
+        $raw = $body->read(self::MAX_BODY_BYTES + 1);
+        if (strlen($raw) > self::MAX_BODY_BYTES) {
+            return $this->empty(413);
+        }
+
+        try {
+            $data = json_decode($raw, true, 32, JSON_THROW_ON_ERROR);
+        } catch (\JsonException) {
+            return $this->empty(400);
+        }
+        if (!\is_array($data) || array_is_list($data)) {
+            return $this->empty(400);
+        }
+        $message = trim($this->str($data['message'] ?? ''));
+        if ($message === '') {
+            return $this->empty(400);
+        }
+
+        $row = [
+            'pid' => 0,
+            'crdate' => time(),
+            'url' => $this->cut($this->str($data['url'] ?? ''), 1024),
+            'message' => $this->cut($message, 2000),
+            'stack' => $this->cut($this->str($data['stack'] ?? ''), 6000),
+            'release' => $this->cut($this->str($data['release'] ?? ''), 100),
+            'user_agent' => $this->cut($this->str($data['userAgent'] ?? $request->getHeaderLine('User-Agent')), 500),
+            'ip' => self::anonymizeIp($ip),
+        ];
+        try {
+            $this->connectionPool->getConnectionForTable(self::TABLE)->insert(self::TABLE, $row);
+        } catch (\Throwable) {
+            // Table missing (extension:setup not run yet) or DB hiccup:
+            // the client gets its 204 anyway - a reporting endpoint must
+            // never turn into a second error in the browser console.
+        }
+
+        return $this->empty(204);
+    }
+
+    /**
+     * IPv4: last octet zeroed (192.0.2.0). IPv6: first three groups
+     * kept (2001:db8:1::). Anything else: empty.
+     */
+    public static function anonymizeIp(string $ip): string
+    {
+        if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false) {
+            $parts = explode('.', $ip);
+            $parts[3] = '0';
+            return implode('.', $parts);
+        }
+        if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) !== false) {
+            $packed = inet_pton($ip);
+            if ($packed === false) {
+                return '';
+            }
+            $hex = bin2hex($packed);
+            $groups = [];
+            for ($i = 0; $i < 3; $i++) {
+                $groups[] = ltrim(substr($hex, $i * 4, 4), '0') ?: '0';
+            }
+            return implode(':', $groups) . '::';
+        }
+        return '';
+    }
+
+    private function str(mixed $value): string
+    {
+        if (\is_string($value)) {
+            return $value;
+        }
+        if (\is_int($value) || \is_float($value) || \is_bool($value)) {
+            return (string)$value;
+        }
+        return '';
+    }
+
+    private function cut(string $value, int $max): string
+    {
+        $value = str_replace("\0", '', $value);
+        return mb_strlen($value) > $max ? mb_substr($value, 0, $max) : $value;
+    }
+
+    private function empty(int $status): ResponseInterface
+    {
+        return (new Response())
+            ->withStatus($status)
+            ->withHeader('Cache-Control', 'no-store');
+    }
+}
diff --git a/packages/vitec/Classes/Widgets/SsrStatsWidget.php b/packages/vitec/Classes/Widgets/SsrStatsWidget.php
index 3957fa0..e8f3f6c 100644
--- a/packages/vitec/Classes/Widgets/SsrStatsWidget.php
+++ b/packages/vitec/Classes/Widgets/SsrStatsWidget.php
@@ -37,6 +37,11 @@ final class SsrStatsWidget implements WidgetInterface
         $avgMs = $this->scalar('SELECT ROUND(AVG(response_ms)) FROM tx_vitec_ssrhealthlog WHERE crdate > ' . $d1 . ' AND ok = 1');
         $maxCache = $this->scalar('SELECT MAX(cache_mb) FROM tx_vitec_ssrhealthlog WHERE crdate > ' . $d7);
 
+        // Browser-side errors reported via POST /api/vitec/client-error
+        // (ClientErrorMiddleware); details in the VITEC SSR module.
+        $clientErrors24h = $this->count('tx_vitec_clienterrorlog', 'crdate > ' . $d1);
+        $clientErrors7d = $this->count('tx_vitec_clienterrorlog', 'crdate > ' . $d7);
+
         $rows = [
             ['Purges (24 h / 7 days)', $purges24h . ' / ' . $purges7d],
             ['of which full purges (7 d)', (string)$full7d],
@@ -47,6 +52,9 @@ final class SsrStatsWidget implements WidgetInterface
                 . ' <small>(' . $ok24h . '/' . $samples24h . ' samples)</small>'],
             ['Avg. response time (24 h)', $avgMs !== null ? $avgMs . ' ms' : '-'],
             ['Max. cache size (7 d)', $maxCache !== null ? $maxCache . ' MB' : '-'],
+            ['Client errors reported (24 h / 7 d)', ($clientErrors24h > 0
+                ? '<span class="badge badge-warning">' . $clientErrors24h . '</span>'
+                : '<span class="badge badge-success">0</span>') . ' / ' . $clientErrors7d],
         ];
 
         $html = '<table class="table table-striped table-sm"><tbody>';
diff --git a/packages/vitec/Configuration/RequestMiddlewares.php b/packages/vitec/Configuration/RequestMiddlewares.php
index 1a70cbb..c4f989f 100755
--- a/packages/vitec/Configuration/RequestMiddlewares.php
+++ b/packages/vitec/Configuration/RequestMiddlewares.php
@@ -56,6 +56,22 @@ return [
                 'typo3/cms-core/normalized-params-attribute',
             ],
         ],
+        // Client error reports from the React frontend:
+        // POST /api/vitec/client-error -> tx_vitec_clienterrorlog, 204
+        // (0072-FE section 4 / 0077-BE). Answers before site resolution,
+        // no session, rate-limited per IP, 8 KB body limit. Placed after
+        // the /_json strip so the prefixed form reaches it as well.
+        'vitec/client-error' => [
+            'target' => \Evomedien\Vitec\Middleware\ClientErrorMiddleware::class,
+            'after' => [
+                'typo3/cms-core/normalized-params-attribute',
+                'vitec/json-prefix-rewrite',
+            ],
+            'before' => [
+                'typo3/cms-frontend/site',
+                'vitec/form-submission',
+            ],
+        ],
         // Outer response filter: Cache-Control: no-cache + ETag/304 for
         // /_json (tickets 0011-FE / 0055-BE).
         'vitec/json-cache-headers' => [
diff --git a/packages/vitec/Resources/Private/Templates/Ssr/Index.html b/packages/vitec/Resources/Private/Templates/Ssr/Index.html
index 8655773..7d25656 100644
--- a/packages/vitec/Resources/Private/Templates/Ssr/Index.html
+++ b/packages/vitec/Resources/Private/Templates/Ssr/Index.html
@@ -140,4 +140,42 @@
     </tbody>
 </table>
 
+<h3>Client errors <small>(last 24 h — {clientErrorCount24h} report<f:if condition="{clientErrorCount24h} != 1">s</f:if>, newest 50 shown)</small></h3>
+<p class="text-muted" style="font-size:11px">
+    Browser-side failures reported by the React frontend via <code>POST /api/vitec/client-error</code>
+    (JS errors, unhandled promise rejections, element error boundaries and "chunk reload" after a deploy).
+    Limited to 30 reports per minute and IP, 8 KB per report; IPs are stored anonymized.
+    Kept for 30 days (cron <code>vitec:client-error-cleanup</code>).
+</p>
+<table class="table table-striped table-sm">
+    <thead><tr><th>Time</th><th>Release</th><th>Message</th><th>Page</th><th>Browser</th><th>IP</th></tr></thead>
+    <tbody>
+    <f:for each="{clientErrors}" as="row">
+        <tr>
+            <td style="white-space:nowrap"><f:format.date format="Y-m-d H:i:s">@{row.crdate}</f:format.date></td>
+            <td><code>{row.release}</code></td>
+            <td>
+                <f:if condition="{row.is_chunk_reload}">
+                    <f:then><span class="badge badge-warning">chunk reload</span> </f:then>
+                    <f:else><span class="badge badge-danger">error</span> </f:else>
+                </f:if>
+                {row.message}
+                <f:if condition="{row.stack}">
+                    <details style="margin-top:4px">
+                        <summary style="cursor:pointer" class="text-muted">stack</summary>
+                        <pre style="font-size:11px;white-space:pre-wrap;max-height:240px;overflow:auto">{row.stack}</pre>
+                    </details>
+                </f:if>
+            </td>
+            <td><a href="{row.url}" target="_blank" rel="noopener" title="{row.url}">{row.path}</a></td>
+            <td title="{row.user_agent}"><small>{row.ua_short}</small></td>
+            <td><small>{row.ip}</small></td>
+        </tr>
+    </f:for>
+    <f:if condition="!{clientErrors}">
+        <tr><td colspan="6" class="text-muted">No client errors reported in the last 24 hours.</td></tr>
+    </f:if>
+    </tbody>
+</table>
+
 </html>
diff --git a/packages/vitec/ext_tables.sql b/packages/vitec/ext_tables.sql
index e53e1d7..da33ef7 100755
--- a/packages/vitec/ext_tables.sql
+++ b/packages/vitec/ext_tables.sql
@@ -499,3 +499,22 @@ CREATE TABLE tx_vitec_ssrhealthlog (
     PRIMARY KEY (uid),
     KEY crdate (crdate)
 );
+
+#
+# Client error reports from the React frontend
+# (POST /api/vitec/client-error, ClientErrorMiddleware; 30-day retention
+# via vitec:client-error-cleanup; shown in the VITEC SSR module)
+#
+CREATE TABLE tx_vitec_clienterrorlog (
+    uid int(11) NOT NULL auto_increment,
+    pid int(11) DEFAULT '0' NOT NULL,
+    crdate int(11) DEFAULT '0' NOT NULL,
+    url varchar(1024) DEFAULT '' NOT NULL,
+    message text,
+    stack text,
+    release varchar(100) DEFAULT '' NOT NULL,
+    user_agent varchar(500) DEFAULT '' NOT NULL,
+    ip varchar(64) DEFAULT '' NOT NULL,
+    PRIMARY KEY (uid),
+    KEY crdate (crdate)
+);