diff --git a/odoo/addons/base/models/ir_qweb.py b/odoo/addons/base/models/ir_qweb.py
index 0fe81af01ad..8e2ef1f41a8 100644
--- a/odoo/addons/base/models/ir_qweb.py
+++ b/odoo/addons/base/models/ir_qweb.py
@@ -636,22 +636,21 @@ class IrQWeb(models.AbstractModel):
         string document that contains ``element``, and ``ref`` if the uniq
         reference of the template (id, t-name or template).
 
-        :param template: template identifier, name or etree
+        :param template: template identifier or etree
         :param options: used to compile the template (the dict available for
             the rendering is frozen)
             ``load`` (function) overrides the load method
         """
+        assert template not in (False, None, ""), "template is required"
+
         # template is an xml etree already
         if isinstance(template, etree._Element):
             element = template
             document = etree.tostring(template, encoding='unicode')
             ref = None
-
         # template is xml as string
-        elif isinstance(template, str) and template.startswith('<'):
-            element = etree.fromstring(template)
-            document = template
-            ref = None
+        elif isinstance(template, str) and '<' in template:
+            raise ValueError('Inline templates must be passed as `etree` documents')
 
         # template is (id or ref) to a database stored template
         else:
diff --git a/odoo/addons/base/tests/test_qweb.py b/odoo/addons/base/tests/test_qweb.py
index 11957e67ca9..b3897c2699c 100644
--- a/odoo/addons/base/tests/test_qweb.py
+++ b/odoo/addons/base/tests/test_qweb.py
@@ -17,6 +17,7 @@ from odoo.tests.common import TransactionCase
 from odoo.addons.base.models.ir_qweb import QWebException, render
 from odoo.tools import misc, mute_logger
 from odoo.tools.json import scriptsafe as json_scriptsafe
+from odoo.exceptions import MissingError
 
 unsafe_eval = eval
 
@@ -1240,6 +1241,51 @@ class TestQWebBasic(TransactionCase):
             self.assertIn('Can not compile expression', error)
             self.assertIn('<div t-esc="abc + def + ("/>', error)
 
+    def test_error_message_3(self):
+        # The format error tells the developer what to do.
+        template = '''<section>
+                    <div t-esc="1+2">
+                        <span>content</span>
+                    </div>
+                </section>'''
+        with self.assertRaises(ValueError):
+            self.env['ir.qweb']._render(template)
+        try:
+            self.env['ir.qweb']._render(template)
+        except ValueError as e:
+            self.assertIn('Inline templates must be passed as `etree` documents', str(e))
+
+        template = '''toto <t t-esc="content"/>'''
+        with self.assertRaises(ValueError):
+            self.env['ir.qweb']._render(template)
+        try:
+            self.env['ir.qweb']._render(template)
+        except ValueError as e:
+            self.assertIn('Inline templates must be passed as `etree` documents', str(e))
+
+    def test_error_message_4(self):
+        # Template record view not found.
+        with self.assertRaises(MissingError):
+            self.env['ir.qweb']._render(-999)
+        try:
+            self.env['ir.qweb']._render(-999)
+        except MissingError as e:
+            self.assertIn('Record does not exist or has been deleted.', str(e))
+
+        with self.assertRaises(ValueError):
+            self.env['ir.qweb']._render('not.wrong_template_xmlid')
+        try:
+            self.env['ir.qweb']._render('not.wrong_template_xmlid')
+        except ValueError as e:
+            self.assertIn('External ID not found in the system', str(e))
+
+        with self.assertRaises(AssertionError):
+            self.env['ir.qweb']._render(False)
+        try:
+            self.env['ir.qweb']._render(False)
+        except AssertionError as e:
+            self.assertIn('template is required', str(e))
+
     def test_call_set(self):
         view0 = self.env['ir.ui.view'].create({
             'name': "dummy",