diff --git a/awx/main/fields.py b/awx/main/fields.py
index ae0d89848a..f7953f5830 100644
--- a/awx/main/fields.py
+++ b/awx/main/fields.py
@@ -420,15 +420,15 @@ def format_ssh_private_key(value):
     # These end in a unicode-encoded final character that gets double
     # escaped due to being in a Python 2 bytestring, and that causes
     # Python's key parsing to barf. Detect this issue and correct it.
-    if value == '$encrypted$':
-        return value
+    if not value or value == '$encrypted$':
+        return True
     if r'\u003d' in value:
         value = value.replace(r'\u003d', '=')
     try:
         validate_ssh_private_key(value)
     except django_exceptions.ValidationError as e:
         raise jsonschema.exceptions.FormatError(e.message)
-    return value
+    return True
 
 
 class CredentialInputField(JSONSchemaField):
@@ -478,6 +478,13 @@ class CredentialInputField(JSONSchemaField):
             return super(CredentialInputField, self).validate(value,
                                                               model_instance)
 
+        # Backwards compatability: in prior versions, if you submit `null` for
+        # a credential field value, it just considers the value an empty string
+        for unset in [key for key, v in model_instance.inputs.items() if not v]:
+            default_value = model_instance.credential_type.default_for_field(unset)
+            if default_value is not None:
+                model_instance.inputs[unset] = default_value
+
         decrypted_values = {}
         for k, v in value.items():
             if all([
diff --git a/awx/main/models/credential.py b/awx/main/models/credential.py
index 7f6b875ae8..938d119faf 100644
--- a/awx/main/models/credential.py
+++ b/awx/main/models/credential.py
@@ -457,6 +457,13 @@ class CredentialType(CommonModelNameNotUnique):
             if field.get('ask_at_runtime', False) is True
         ]
 
+    def default_for_field(self, field_id):
+        for field in self.inputs.get('fields', []):
+            if field['id'] == field_id:
+                if 'choices' in field:
+                    return field['choices'][0]
+                return {'string': '', 'boolean': False}[field['type']]
+
     @classmethod
     def default(cls, f):
         func = functools.partial(f, cls)
diff --git a/awx/main/tests/functional/api/test_credential.py b/awx/main/tests/functional/api/test_credential.py
index 4a95223c21..4a94777bb8 100644
--- a/awx/main/tests/functional/api/test_credential.py
+++ b/awx/main/tests/functional/api/test_credential.py
@@ -1,3 +1,5 @@
+import itertools
+
 import mock # noqa
 import pytest
 
@@ -707,6 +709,59 @@ def test_inputs_cannot_contain_extra_fields(get, post, organization, admin, cred
     assert "'invalid_field' was unexpected" in response.data['inputs'][0]
 
 
+@pytest.mark.django_db
+@pytest.mark.parametrize('field_name, field_value', itertools.product(
+    ['username', 'password', 'ssh_key_data', 'ssh_key_unlock', 'become_method', 'become_username', 'become_password'],  # noqa
+    ['', None]
+))
+def test_nullish_field_data(get, post, organization, admin, field_name, field_value):
+    ssh = CredentialType.defaults['ssh']()
+    ssh.save()
+    params = {
+        'name': 'Best credential ever',
+        'credential_type': ssh.pk,
+        'organization': organization.id,
+        'inputs': {
+            field_name: field_value
+        }
+    }
+    response = post(
+        reverse('api:credential_list', kwargs={'version': 'v2'}),
+        params,
+        admin
+    )
+    assert response.status_code == 201
+
+    assert Credential.objects.count() == 1
+    cred = Credential.objects.all()[:1].get()
+    assert getattr(cred, field_name) == ''
+
+
+@pytest.mark.django_db
+@pytest.mark.parametrize('field_value', ['', None, False])
+def test_falsey_field_data(get, post, organization, admin, field_value):
+    net = CredentialType.defaults['net']()
+    net.save()
+    params = {
+        'name': 'Best credential ever',
+        'credential_type': net.pk,
+        'organization': organization.id,
+        'inputs': {
+            'authorize': field_value
+        }
+    }
+    response = post(
+        reverse('api:credential_list', kwargs={'version': 'v2'}),
+        params,
+        admin
+    )
+    assert response.status_code == 201
+
+    assert Credential.objects.count() == 1
+    cred = Credential.objects.all()[:1].get()
+    assert cred.authorize is False
+
+
 #
 # SCM Credentials
 #