diff --git a/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js b/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js
index ccad6a13cef..80b5c13f349 100644
--- a/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js
+++ b/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js
@@ -2,6 +2,7 @@
 import React from 'react'
 import ArrayFunctions from 'part:@sanity/form-builder/input/array/functions'
 import {map} from 'rxjs/operators'
+import {isPlainObject} from 'lodash'
 import type {Uploader} from '../../sanity/uploads/typedefs'
 import type {Marker, Type} from '../../typedefs'
 import type {Path} from '../../typedefs/path'
@@ -261,6 +262,15 @@ export default class ArrayInput extends React.Component<Props, State> {
     onChange(PatchEvent.from(...patches))
   }
 
+  handleRemoveNonObjectValues = () => {
+    const {onChange, value} = this.props
+    const nonObjects = value
+      .reduce((acc, val, i) => (isPlainObject(val) ? acc : acc.concat(i)), [])
+      .reverse()
+    const patches = nonObjects.map(index => unset([index]))
+    onChange(PatchEvent.from(...patches))
+  }
+
   handleUpload = ({file, type, uploader}) => {
     const {onChange} = this.props
     const item = createProtoValue(type)
@@ -280,6 +290,34 @@ export default class ArrayInput extends React.Component<Props, State> {
 
   render() {
     const {type, level, markers, readOnly, onChange, value} = this.props
+    const hasNonObjectValues = (value || []).some(item => !isPlainObject(item))
+    if (hasNonObjectValues) {
+      return (
+        <Fieldset
+          legend={type.title}
+          description={type.description}
+          level={level}
+          tabIndex={0}
+          onFocus={this.handleFocus}
+          ref={this.setElement}
+          markers={markers}
+        >
+          <div className={styles.nonObjectsWarning}>
+            Some items in this list are not objects. We need to remove them before the list can be
+            edited.
+            <div className={styles.removeNonObjectsButtonWrapper}>
+              <Button onClick={this.handleRemoveNonObjectValues}>Remove non-object values</Button>
+            </div>
+            <Details title={<b>Why is this happening?</b>}>
+              This usually happens when items are created through an API client from outside the
+              Content Studio and sets invalid data, or a custom input component have inserted
+              incorrect values into the list.
+            </Details>
+          </div>
+        </Fieldset>
+      )
+    }
+
     const hasMissingKeys = (value || []).some(item => !item._key)
     if (hasMissingKeys) {
       return (
@@ -296,9 +334,7 @@ export default class ArrayInput extends React.Component<Props, State> {
             Some items in this list are missing their keys. We need to fix this before the list can
             be edited.
             <div className={styles.fixMissingKeysButtonWrapper}>
-              <Button onClick={this.handleFixMissingKeys}>
-                Fix missing keys
-              </Button>
+              <Button onClick={this.handleFixMissingKeys}>Fix missing keys</Button>
             </div>
             <Details title={<b>Why is this happening?</b>}>
               This usually happens when items are created through the API client from outside the
diff --git a/packages/@sanity/form-builder/src/inputs/ArrayInput/styles/ArrayInput.css b/packages/@sanity/form-builder/src/inputs/ArrayInput/styles/ArrayInput.css
index 28380f29479..c3596327d48 100644
--- a/packages/@sanity/form-builder/src/inputs/ArrayInput/styles/ArrayInput.css
+++ b/packages/@sanity/form-builder/src/inputs/ArrayInput/styles/ArrayInput.css
@@ -75,3 +75,12 @@
 .fixMissingKeysButtonWrapper {
   margin: 1em 0;
 }
+
+.nonObjectsWarning {
+  composes: warning;
+  padding: 1em;
+}
+
+.removeNonObjectsButtonWrapper {
+  composes: fixMissingKeysButtonWrapper;
+}
diff --git a/packages/@sanity/validation/src/validateDocument.js b/packages/@sanity/validation/src/validateDocument.js
index 6e56d6cbca0..d7cb31ce6b2 100644
--- a/packages/@sanity/validation/src/validateDocument.js
+++ b/packages/@sanity/validation/src/validateDocument.js
@@ -90,7 +90,7 @@ function validateArray(items, type, path, options) {
   }
   // Validate items within array
   const itemChecks = items.map((item, i) => {
-    const pathSegment = item._key ? {_key: item._key} : i
+    const pathSegment = item && item._key ? {_key: item._key} : i
     const itemType = resolveTypeForArrayItem(item, type.of)
     const itemPath = appendPath(path, [pathSegment])
     return validateItem(item, itemType, itemPath, {
@@ -104,6 +104,17 @@ function validateArray(items, type, path, options) {
 }
 
 function validatePrimitive(item, type, path, options) {
+  if (!type) {
+    return [
+      {
+        type: 'validation',
+        level: 'error',
+        path,
+        item: new ValidationError('Unable to resolve type for item')
+      }
+    ]
+  }
+
   if (!type.validation) {
     return []
   }
@@ -118,7 +129,7 @@ function validatePrimitive(item, type, path, options) {
 }
 
 function resolveTypeForArrayItem(item, candidates) {
-  const primitive = !item._type && Type.string(item).toLowerCase()
+  const primitive = !item || (!item._type && Type.string(item).toLowerCase())
   if (primitive) {
     return candidates.find(candidate => candidate.jsonType === primitive)
   }