diff --git a/readthedocs/config/config.py b/readthedocs/config/config.py
index 9b7c1a0c782..884945418f0 100644
--- a/readthedocs/config/config.py
+++ b/readthedocs/config/config.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # pylint: disable=too-many-lines
 
 """Build configuration for rtd."""
@@ -37,6 +36,7 @@
     validate_string,
 )
 
+
 __all__ = (
     'ALL',
     'load',
@@ -44,6 +44,7 @@
     'BuildConfigV2',
     'ConfigError',
     'ConfigOptionNotSupportedError',
+    'ConfigFileNotFound',
     'InvalidConfig',
     'PIP',
     'SETUPTOOLS',
@@ -58,7 +59,7 @@
 VERSION_INVALID = 'version-invalid'
 CONFIG_SYNTAX_INVALID = 'config-syntax-invalid'
 CONFIG_REQUIRED = 'config-required'
-CONF_FILE_REQUIRED = 'conf-file-required'
+CONFIG_FILE_REQUIRED = 'config-file-required'
 PYTHON_INVALID = 'python-invalid'
 SUBMODULES_INVALID = 'submodules-invalid'
 INVALID_KEYS_COMBINATION = 'invalid-keys-combination'
@@ -87,6 +88,17 @@ def __init__(self, message, code):
         super().__init__(message)
 
 
+class ConfigFileNotFound(ConfigError):
+
+    """Error when we can't find a configuration file."""
+
+    def __init__(self, directory):
+        super().__init__(
+            f"Configuration file not found in: {directory}",
+            CONFIG_FILE_REQUIRED,
+        )
+
+
 class ConfigOptionNotSupportedError(ConfigError):
 
     """Error for unsupported configuration options in a version."""
@@ -298,7 +310,6 @@ class BuildConfigV1(BuildConfigBase):
 
     """Version 1 of the configuration file."""
 
-    CONF_FILE_REQUIRED_MESSAGE = 'Missing key "conf_file"'
     PYTHON_INVALID_MESSAGE = '"python" section must be a mapping.'
     PYTHON_EXTRA_REQUIREMENTS_INVALID_MESSAGE = (
         '"python.extra_requirements" section must be a list.'
@@ -1104,14 +1115,14 @@ def load(path, env_config):
     filename = find_one(path, CONFIG_FILENAME_REGEX)
 
     if not filename:
-        raise ConfigError('No configuration file found', code=CONFIG_REQUIRED)
+        raise ConfigFileNotFound(path)
     with open(filename, 'r') as configuration_file:
         try:
             config = parse(configuration_file.read())
         except ParseError as error:
             raise ConfigError(
                 'Parse error in {filename}: {message}'.format(
-                    filename=filename,
+                    filename=os.path.relpath(filename, path),
                     message=str(error),
                 ),
                 code=CONFIG_SYNTAX_INVALID,
diff --git a/readthedocs/config/tests/test_config.py b/readthedocs/config/tests/test_config.py
index 3ad5cfe8a9d..404cf691211 100644
--- a/readthedocs/config/tests/test_config.py
+++ b/readthedocs/config/tests/test_config.py
@@ -15,14 +15,17 @@
     BuildConfigV1,
     BuildConfigV2,
     ConfigError,
+    ConfigFileNotFound,
     ConfigOptionNotSupportedError,
     InvalidConfig,
     load,
 )
 from readthedocs.config.config import (
+    CONFIG_FILE_REQUIRED,
     CONFIG_FILENAME_REGEX,
     CONFIG_NOT_SUPPORTED,
     CONFIG_REQUIRED,
+    CONFIG_SYNTAX_INVALID,
     INVALID_KEY,
     PYTHON_INVALID,
     VERSION_INVALID,
@@ -73,9 +76,9 @@ def get_build_config(config, env_config=None, source_file='readthedocs.yml'):
 def test_load_no_config_file(tmpdir, files):
     apply_fs(tmpdir, files)
     base = str(tmpdir)
-    with raises(ConfigError) as e:
+    with raises(ConfigFileNotFound) as e:
         load(base, {})
-    assert e.value.code == CONFIG_REQUIRED
+    assert e.value.code == CONFIG_FILE_REQUIRED
 
 
 def test_load_empty_config_file(tmpdir):
@@ -136,6 +139,27 @@ def test_load_unknow_version(tmpdir):
     assert excinfo.value.code == VERSION_INVALID
 
 
+def test_load_raise_exception_invalid_syntax(tmpdir):
+    apply_fs(
+        tmpdir, {
+            'readthedocs.yml': textwrap.dedent('''
+                version: 2
+                python:
+                  install:
+                    - method: pip
+                      path: .
+                        # bad indentation here
+                        extra_requirements:
+                          - build
+            '''),
+        },
+    )
+    base = str(tmpdir)
+    with raises(ConfigError) as excinfo:
+        load(base, {})
+    assert excinfo.value.code == CONFIG_SYNTAX_INVALID
+
+
 def test_yaml_extension(tmpdir):
     """Make sure loading the 'readthedocs' file with a 'yaml' extension."""
     apply_fs(
diff --git a/readthedocs/doc_builder/config.py b/readthedocs/doc_builder/config.py
index 9e002d561d7..5f57a4402b1 100644
--- a/readthedocs/doc_builder/config.py
+++ b/readthedocs/doc_builder/config.py
@@ -1,10 +1,8 @@
-# -*- coding: utf-8 -*-
-
 """An API to load config from a readthedocs.yml file."""
 
 from os import path
 
-from readthedocs.config import BuildConfigV1, ConfigError, InvalidConfig
+from readthedocs.config import BuildConfigV1, ConfigFileNotFound
 from readthedocs.config import load as load_config
 from readthedocs.projects.models import ProjectConfigurationError
 
@@ -59,10 +57,9 @@ def load_yaml_config(version):
             path=checkout_path,
             env_config=env_config,
         )
-    except InvalidConfig:
-        # This is a subclass of ConfigError, so has to come first
-        raise
-    except ConfigError:
+    except ConfigFileNotFound:
+        # Dafault to use v1 with some defaults from the web interface
+        # if we don't find a configuration file.
         config = BuildConfigV1(
             env_config=env_config,
             raw_config={},