diff --git a/client/src/lib/sandboxed-mosaico-root.js b/client/src/lib/sandboxed-mosaico-root.js
index 3109d08d..6e47375d 100644
--- a/client/src/lib/sandboxed-mosaico-root.js
+++ b/client/src/lib/sandboxed-mosaico-root.js
@@ -82,6 +82,12 @@ class MosaicoSandbox extends Component {
             };
         });
 
+        // Custom convertedUrl (https://github.com/voidlabs/mosaico/blob/a359e263f1af5cf05e2c2d56c771732f2ef6c8c6/src/js/app.js#L42)
+        // which does not complain about mismatch of domains between TRUSTED and PUBLIC
+        plugins.push(viewModel => {
+            ko.bindingHandlers.wysiwygSrc.convertedUrl = (src, method, width, height) => getTrustedUrl(`mosaico/img?src=${encodeURIComponent(src)}&method=${encodeURIComponent(method)}&params=${width},${height}`);
+        });
+
         plugins.unshift(vm => {
             // This is an override of the default paths in Mosaico
             vm.logoPath = getTrustedUrl('static/mosaico/img/mosaico32.png');
diff --git a/server/app-builder.js b/server/app-builder.js
index a9243f4a..55c84c50 100644
--- a/server/app-builder.js
+++ b/server/app-builder.js
@@ -320,93 +320,49 @@ function createApp(appType) {
 
     app.use('/', index.getRouter(appType));
 
-    // Error handlers
-    if (app.get('env') === 'development' || app.get('env') === 'test') {
-        // development error handler
-        // will print stacktrace
-        app.use((err, req, res, next) => {
-            if (!err) {
-                return next();
+    app.use((err, req, res, next) => {
+        if (!err) {
+            return next();
+        }
+
+        if (req.needsRESTJSONResponse) {
+            const resp = {
+                message: err.message,
+                error: config.sendStacktracesToClient ? err : {}
+            };
+
+            if (err instanceof interoperableErrors.InteroperableError) {
+                resp.type = err.type;
+                resp.data = err.data;
             }
 
-            if (req.needsRESTJSONResponse) {
-                const resp = {
-                    message: err.message,
-                    error: err
-                };
+            log.verbose('HTTP', err);
+            res.status(err.status || 500).json(resp);
 
-                if (err instanceof interoperableErrors.InteroperableError) {
-                    resp.type = err.type;
-                    resp.data = err.data;
-                }
+        } else if (req.needsAPIJSONResponse) {
+            const resp = {
+                error: err.message || err,
+                data: []
+            };
 
-                res.status(err.status || 500).json(resp);
+            log.verbose('HTTP', err);
+            return res.status(err.status || 500).json(resp);
 
-            } else if (req.needsAPIJSONResponse) {
-                const resp = {
-                    error: err.message || err,
-                    data: []
-                };
-
-                return status(err.status || 500).json(resp);
+        } else {
+            // TODO: Render interoperable errors using a special client that does internationalization of the error message
 
+            if (err instanceof interoperableErrors.NotLoggedInError) {
+                return res.redirect(getTrustedUrl('/login?next=' + encodeURIComponent(req.originalUrl)));
             } else {
-                if (err instanceof interoperableErrors.NotLoggedInError) {
-                    return res.redirect(getTrustedUrl('/login?next=' + encodeURIComponent(req.originalUrl)));
-                } else {
-                    res.status(err.status || 500);
-                    res.render('error', {
-                        message: err.message,
-                        error: err
-                    });
-                }
-            }
-
-        });
-    } else {
-        // production error handler
-        // no stacktraces leaked to user
-        app.use((err, req, res, next) => {
-            if (!err) {
-                return next();
-            }
-
-            if (req.needsRESTJSONResponse) {
-                const resp = {
+                log.verbose('HTTP', err);
+                res.status(err.status || 500);
+                res.render('error', {
                     message: err.message,
-                    error: {}
-                };
-
-                if (err instanceof interoperableErrors.InteroperableError) {
-                    resp.type = err.type;
-                    resp.data = err.data;
-                }
-
-                res.status(err.status || 500).json(resp);
-
-            } else if (req.needsAPIJSONResponse) {
-                const resp = {
-                    error: err.message || err,
-                    data: []
-                };
-
-                return res.status(err.status || 500).json(resp);
-
-            } else {
-                // TODO: Render interoperable errors using a special client that does internationalization of the error message
-
-                if (err instanceof interoperableErrors.NotLoggedInError) {
-                    return res.redirect(getTrustedUrl('/login?next=' + encodeURIComponent(req.originalUrl)));
-                } else {
-                    res.status(err.status || 500);
-                    res.render('error', {
-                        message: err.message,
-                        error: {}
-                    });
-                }
+                    error: config.sendStacktracesToClient ? err : {}
+                });
             }
-        });
-    }
+        }
+    });
 
     return app;
 }
diff --git a/server/config/default.yaml b/server/config/default.yaml
index 36cf8f2f..9bc88cf3 100644
--- a/server/config/default.yaml
+++ b/server/config/default.yaml
@@ -73,6 +73,7 @@ redis:
 log:
   # silly|verbose|info|http|warn|error|silent
   level: info
+  sendStacktracesToClient: false
 
 www:
   # HTTP port to listen on for trusted requests (logged-in users)
diff --git a/server/index.js b/server/index.js
index 5a063a28..09167f24 100644
--- a/server/index.js
+++ b/server/index.js
@@ -24,6 +24,7 @@ const { AppType } = require('../shared/app');
 const builtinZoneMta = require('./lib/builtin-zone-mta');
 
 const { uploadedFilesDir } = require('./lib/file-helpers');
+const { filesDir } = require('./models/files');
 
 const trustedPort = config.www.trustedPort;
 const sandboxPort = config.www.sandboxPort;
@@ -113,6 +114,7 @@ dbcheck(err => { // Check if database needs upgrading before starting the server
                             startHTTPServer(AppType.SANDBOXED, 'sandbox', sandboxPort, () =>
                                 startHTTPServer(AppType.PUBLIC, 'public', publicPort, async () => {
 
+                                    await privilegeHelpers.ensureMailtrainDir(filesDir);
                                     await privilegeHelpers.ensureMailtrainDir(uploadedFilesDir);
 
                                     privilegeHelpers.dropRootPrivileges();
diff --git a/server/routes/sandboxed-mosaico.js b/server/routes/sandboxed-mosaico.js
index 20de35de..aa8d7755 100644
--- a/server/routes/sandboxed-mosaico.js
+++ b/server/routes/sandboxed-mosaico.js
@@ -156,7 +156,6 @@ function getRouter(appType) {
         // This is a fallback to versafix-1 if the block thumbnail is not defined by the template
         router.use('/templates/:mosaicoTemplateId/edres', express.static(path.join(__dirname, '..', '..', 'client', 'static', 'mosaico', 'templates', 'versafix-1', 'edres')));
 
-
         fileHelpers.installUploadHandler(router, '/upload/:type/:entityId', files.ReplacementBehavior.RENAME, null, 'file', resp => {
             return {
                 files: resp.files.map(f => ({name: f.name, url: f.url, size: f.size, thumbnailUrl: f.thumbnailUrl}))