diff --git a/src/libsync/creds/httpcredentials.cpp b/src/libsync/creds/httpcredentials.cpp
index ca2a1982a9..6d0899aeab 100644
--- a/src/libsync/creds/httpcredentials.cpp
+++ b/src/libsync/creds/httpcredentials.cpp
@@ -117,6 +117,7 @@ HttpCredentials::HttpCredentials(const QString &user, const QString &password, c
     , _clientSslKey(key)
     , _clientSslCertificate(certificate)
     , _keychainMigration(false)
+    , _retryOnKeyChainError(false)
 {
 }
 
@@ -219,6 +220,21 @@ void HttpCredentials::deleteOldKeychainEntries()
 
 void HttpCredentials::slotReadClientCertPEMJobDone(QKeychain::Job *incoming)
 {
+#if defined(Q_OS_UNIX) && !defined(Q_OS_MAC)
+    Q_ASSERT(!incoming->insecureFallback()); // If insecureFallback is set, the next test would be pointless
+    if (_retryOnKeyChainError && (incoming->error() == QKeychain::NoBackendAvailable
+            || incoming->error() == QKeychain::OtherError)) {
+        // Could be that the backend was not yet available. Wait some extra seconds.
+        // (Issues #4274 and #6522)
+        // (For kwallet, the error is OtherError instead of NoBackendAvailable, maybe a bug in QtKeychain)
+        qCInfo(lcHttpCredentials) << "Backend unavailable (yet?) Retrying in a few seconds." << incoming->errorString();
+        QTimer::singleShot(10000, this, &HttpCredentials::fetchFromKeychainHelper);
+        _retryOnKeyChainError = false;
+        return;
+    }
+    _retryOnKeyChainError = false;
+#endif
+
     // Store PEM in memory
     ReadPasswordJob *readJob = static_cast<ReadPasswordJob *>(incoming);
     if (readJob->error() == NoError && readJob->binaryData().length() > 0) {
diff --git a/src/libsync/creds/httpcredentials.h b/src/libsync/creds/httpcredentials.h
index 4ed8c114be..b71edf6ca8 100644
--- a/src/libsync/creds/httpcredentials.h
+++ b/src/libsync/creds/httpcredentials.h
@@ -141,6 +141,7 @@ protected:
     QSslKey _clientSslKey;
     QSslCertificate _clientSslCertificate;
     bool _keychainMigration;
+    bool _retryOnKeyChainError = true; // true if we haven't done yet any reading from keychain
 };