diff --git a/addons/mail/wizard/mail_template_preview.py b/addons/mail/wizard/mail_template_preview.py
index 79644ce3e8f..5916cabdc69 100644
--- a/addons/mail/wizard/mail_template_preview.py
+++ b/addons/mail/wizard/mail_template_preview.py
@@ -43,7 +43,7 @@ class MailTemplatePreview(models.TransientModel):
     resource_ref = fields.Reference(string='Record', selection='_selection_target_model')
     lang = fields.Selection(_selection_languages, string='Template Preview Language')
     no_record = fields.Boolean('No Record', compute='_compute_no_record')
-    error_msg = fields.Char('Error Message', readonly=True)
+    error_msg = fields.Char('Error Message', compute='_compute_mail_template_fields')
     # Fields same than the mail.template model, computed with resource_ref and lang
     subject = fields.Char('Subject', compute='_compute_mail_template_fields')
     email_from = fields.Char('From', compute='_compute_mail_template_fields', help="Sender address")
@@ -82,7 +82,7 @@ class MailTemplatePreview(models.TransientModel):
                 )
                 self._set_mail_attributes(values=mail_values)
             self.error_msg = False
-        except UserError as user_error:
+        except (ValueError, UserError) as user_error:
             self._set_mail_attributes()
             self.error_msg = user_error.args[0]
         finally:
diff --git a/addons/mail/wizard/mail_template_preview_views.xml b/addons/mail/wizard/mail_template_preview_views.xml
index 228c97956f5..90865d69061 100644
--- a/addons/mail/wizard/mail_template_preview_views.xml
+++ b/addons/mail/wizard/mail_template_preview_views.xml
@@ -8,7 +8,7 @@
                 <form string="Email Preview">
                     <h3>Preview of <field name="mail_template_id" readonly="1" nolabel="1" options="{'no_open' : True}"/></h3>
                     <div class="alert alert-danger" role="alert" attrs="{'invisible' : [('error_msg', '=', False)]}">
-                        <field name="error_msg" />
+                        <field name="error_msg"/>
                     </div>
                     <field name="no_record" invisible="1"/>
                     <div class="container">