diff --git a/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp b/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp
--- a/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp
+++ b/libdiscover/backends/FlatpakBackend/FlatpakBackend.cpp
@@ -878,6 +878,10 @@
         FlatpakFetchDataJob *job = new FlatpakFetchDataJob(flatpakInstallation, resource, FlatpakFetchDataJob::FetchSize);
         connect(job, &FlatpakFetchDataJob::finished, job, &FlatpakFetchDataJob::deleteLater);
         connect(job, &FlatpakFetchDataJob::jobFetchSizeFinished, this, &FlatpakBackend::onFetchSizeFinished);
+        connect(job, &FlatpakFetchDataJob::jobFetchSizeFailed, [resource] () {
+            resource->setDownloadSize(-2);
+            resource->setInstalledSize(-2);
+        });
         job->start();
     }
 
@@ -928,6 +932,7 @@
 ResultsStream * FlatpakBackend::search(const AbstractResourcesBackend::Filters &filter)
 {
     QVector<AbstractResource*> ret;
+
     foreach(AbstractResource* r, m_resources) {
         if (qobject_cast<FlatpakResource*>(r)->type() == FlatpakResource::Runtime && filter.state != AbstractResource::Upgradeable) {
             continue;
diff --git a/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.h b/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.h
--- a/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.h
+++ b/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.h
@@ -46,7 +46,9 @@
     void run() override;
 
 Q_SIGNALS:
+    void jobFetchMetadataFailed();
     void jobFetchMetadataFinished(FlatpakInstallation *installation, FlatpakResource *resource, const QByteArray &metadata);
+    void jobFetchSizeFailed();
     void jobFetchSizeFinished(FlatpakResource *resource, int downloadSize, int installedSize);
 
 private:
diff --git a/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.cpp b/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.cpp
--- a/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.cpp
+++ b/libdiscover/backends/FlatpakBackend/FlatpakFetchDataJob.cpp
@@ -53,11 +53,13 @@
 
         if (m_app->origin().isEmpty()) {
             qWarning() << "Failed to get metadata file because of missing origin";
+            Q_EMIT jobFetchMetadataFailed();
             return;
         }
 
         fakeRef = createFakeRef(m_app);
         if (!fakeRef) {
+            Q_EMIT jobFetchMetadataFailed();
             return;
         }
 
@@ -67,11 +69,13 @@
             metadataContent = QByteArray((char *)g_bytes_get_data(data, &len));
         } else {
             qWarning() << "Failed to get metadata file: " << localError->message;
+            Q_EMIT jobFetchMetadataFailed();
             return;
         }
 
         if (metadataContent.isEmpty()) {
             qWarning() << "Failed to get metadata file: empty metadata";
+            Q_EMIT jobFetchMetadataFailed();
             return;
         }
 
@@ -83,12 +87,14 @@
 
         ref = createFakeRef(m_app);
         if (!ref) {
+            Q_EMIT jobFetchSizeFailed();
             return;
         }
 
         if (!flatpak_installation_fetch_remote_size_sync(m_installation, m_app->origin().toStdString().c_str(),
                                                          ref, &downloadSize, &installedSize, m_cancellable, &localError)) {
             qWarning() << "Failed to get remote size of " << m_app->name() << ": " << localError->message;
+            Q_EMIT jobFetchSizeFailed();
             return;
         }
 
diff --git a/libdiscover/backends/FlatpakBackend/FlatpakResource.cpp b/libdiscover/backends/FlatpakBackend/FlatpakResource.cpp
--- a/libdiscover/backends/FlatpakBackend/FlatpakResource.cpp
+++ b/libdiscover/backends/FlatpakBackend/FlatpakResource.cpp
@@ -45,8 +45,8 @@
 FlatpakResource::FlatpakResource(AppStream::Component *component, FlatpakBackend *parent)
     : AbstractResource(parent)
     , m_appdata(component)
-    , m_downloadSize(0)
-    , m_installedSize(0)
+    , m_downloadSize(-1)
+    , m_installedSize(-1)
     , m_scope(FlatpakResource::System)
     , m_state(AbstractResource::None)
     , m_type(FlatpakResource::DesktopApp)
@@ -352,9 +352,21 @@
 {
     KFormat f;
     if (!isInstalled() || canUpgrade()) {
-        return i18nc("@info app size", "%1 to download, %2 on disk", f.formatByteSize(downloadSize()), f.formatByteSize(installedSize()));
+        if (downloadSize() == -1 || installedSize() == -1) {
+            return i18n("Retrieving size information");
+        } else if (downloadSize() == -2 || installedSize() == -2) {
+            return i18n("Unknown size");
+        } else {
+            return i18nc("@info app size", "%1 to download, %2 on disk", f.formatByteSize(downloadSize()), f.formatByteSize(installedSize()));
+        }
     } else {
-        return i18nc("@info app size", "%1 on disk", f.formatByteSize(installedSize()));
+        if (installedSize() == -1) {
+            return i18n("Retrieving size information");
+        } else if (installedSize() == -2) {
+            return i18n("Unknown size");
+        } else {
+            return i18nc("@info app size", "%1 on disk", f.formatByteSize(installedSize()));
+        }
     }
 }