diff --git a/README.md b/README.md
index df5611e..8046300 100644
--- a/README.md
+++ b/README.md
@@ -1187,7 +1187,7 @@ $user->removeAvatar();                                                  // back
 | 401 | `unauthenticated` |
 | 403 | `missing_scope` (no `user` scope), `user_token_required` (an app token: there is no user to change) |
 | 413 | `avatar_too_large` (the upload is larger than the server accepts) |
-| 422 | `ValidationFailedException`, codes per field: `name_invalid`, `username_taken`, `username_invalid`, `email_taken`, `email_invalid`, `avatar_invalid`, `avatar_too_large`, `crop_invalid`, else `validation_failed` |
+| 422 | `ValidationFailedException`, codes per field: `name_invalid`, `username_taken`, `username_invalid`, `email_taken`, `email_invalid`, `avatar_invalid`, `avatar_too_large`, `crop_invalid` (keyed by `crop.x`, `crop.y` or `crop.size`; `errorCodeFor('crop')` finds it), else `validation_failed` |
 | 429 | `too_many_requests` |
 
 Branch on the codes, the messages are for people and may change.
diff --git a/README.stub b/README.stub
index bc17847..16dd144 100644
--- a/README.stub
+++ b/README.stub
@@ -1187,7 +1187,7 @@ $user->removeAvatar();                                                  // back
 | 401 | `unauthenticated` |
 | 403 | `missing_scope` (no `user` scope), `user_token_required` (an app token: there is no user to change) |
 | 413 | `avatar_too_large` (the upload is larger than the server accepts) |
-| 422 | `ValidationFailedException`, codes per field: `name_invalid`, `username_taken`, `username_invalid`, `email_taken`, `email_invalid`, `avatar_invalid`, `avatar_too_large`, `crop_invalid`, else `validation_failed` |
+| 422 | `ValidationFailedException`, codes per field: `name_invalid`, `username_taken`, `username_invalid`, `email_taken`, `email_invalid`, `avatar_invalid`, `avatar_too_large`, `crop_invalid` (keyed by `crop.x`, `crop.y` or `crop.size`; `errorCodeFor('crop')` finds it), else `validation_failed` |
 | 429 | `too_many_requests` |
 
 Branch on the codes, the messages are for people and may change.
diff --git a/src/Id/Concerns/ManagesProfile.php b/src/Id/Concerns/ManagesProfile.php
index b871f44..6ff2cdc 100644
--- a/src/Id/Concerns/ManagesProfile.php
+++ b/src/Id/Concerns/ManagesProfile.php
@@ -72,9 +72,10 @@ trait ManagesProfile
      * @param array{x: int, y: int, size: int}|null $crop the square to use, in pixels of the
      *     upright picture; the centre without one
      * @throws ValidationFailedException 422 with the codes "avatar_invalid", "avatar_too_large",
-     *     "crop_invalid"
+     *     "crop_invalid" (keyed by crop.x, crop.y or crop.size; errorCodeFor('crop') finds them)
      * @throws ApiException 413 "avatar_too_large", 401, 403 "missing_scope", "user_token_required",
      *     429 "too_many_requests" (also more than 10 uploads an hour)
+     * @throws \RuntimeException when the file can't be opened (nothing is sent then)
      */
     public function uploadAvatar(string|SplFileInfo $file, ?array $crop = null): User
     {
@@ -129,4 +130,4 @@ trait ManagesProfile
 
         return new User($result->data);
     }
-}
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Id/Exceptions/ValidationFailedException.php b/src/Id/Exceptions/ValidationFailedException.php
index f9ffd6a..7c6b925 100644
--- a/src/Id/Exceptions/ValidationFailedException.php
+++ b/src/Id/Exceptions/ValidationFailedException.php
@@ -19,9 +19,25 @@ class ValidationFailedException extends ApiException
         return is_object($codes) || is_array($codes) ? array_map('strval', (array) $codes) : [];
     }
 
+    /**
+     * The code of $field, or of its first failed sub-field when the codes are keyed by those
+     * (`crop` finds `crop.x`, `crop.y` or `crop.size`).
+     */
     public function errorCodeFor(string $field): ?string
     {
-        return $this->errorCodes()[$field] ?? null;
+        $codes = $this->errorCodes();
+
+        if (isset($codes[$field])) {
+            return $codes[$field];
+        }
+
+        foreach ($codes as $key => $code) {
+            if (str_starts_with((string) $key, $field . '.')) {
+                return $code;
+            }
+        }
+
+        return null;
     }
 
     /**
diff --git a/tests/Id/UserProfileTest.php b/tests/Id/UserProfileTest.php
index a7c94de..bea1366 100644
--- a/tests/Id/UserProfileTest.php
+++ b/tests/Id/UserProfileTest.php
@@ -198,6 +198,36 @@ class UserProfileTest extends TestCase
         }
     }
 
+    public function test_crop_codes_are_found_under_the_crop_field(): void
+    {
+        $path = tempnam(sys_get_temp_dir(), 'avatar');
+        file_put_contents($path, 'a picture');
+        $this->respond(422, $this->validationError(['crop.size' => 'crop_invalid']));
+
+        try {
+            $this->owner()->uploadAvatar($path, ['x' => 0, 'y' => 0]);
+            $this->fail('No exception thrown');
+        } catch (ValidationFailedException $e) {
+            $this->assertSame('crop_invalid', $e->errorCodeFor('crop'));
+            $this->assertSame('crop_invalid', $e->errorCodeFor('crop.size'));
+            $this->assertNull($e->errorCodeFor('cro'));
+            $this->assertNull($e->errorCodeFor('avatar'));
+        } finally {
+            unlink($path);
+        }
+    }
+
+    public function test_an_unreadable_file_throws_before_anything_is_sent(): void
+    {
+        try {
+            $this->owner()->uploadAvatar(sys_get_temp_dir() . '/missing-avatar-' . uniqid() . '.png');
+            $this->fail('No exception thrown');
+        } catch (\RuntimeException $e) {
+            $this->assertNotInstanceOf(ApiException::class, $e);
+            $this->assertCount(0, $this->sent);
+        }
+    }
+
     public function test_remove_avatar_deletes_the_upload_and_clears_the_cache(): void
     {
         $owner = $this->owner();