diff --git a/src/wp-includes/ai-client/class-wp-ai-client-prompt-builder.php b/src/wp-includes/ai-client/class-wp-ai-client-prompt-builder.php
index da7858dd76555..39f2338feb7b5 100644
--- a/src/wp-includes/ai-client/class-wp-ai-client-prompt-builder.php
+++ b/src/wp-includes/ai-client/class-wp-ai-client-prompt-builder.php
@@ -185,9 +185,9 @@ class WP_AI_Client_Prompt_Builder {
 	public function __construct( ProviderRegistry $registry, $prompt = null ) {
 		try {
 			$this->builder = new PromptBuilder( $registry, $prompt, AiClient::getEventDispatcher() );
-		} catch ( Exception $e ) {
+		} catch ( Throwable $e ) {
 			$this->builder = new PromptBuilder( $registry, null, AiClient::getEventDispatcher() );
-			$this->error   = $this->exception_to_wp_error( $e );
+			$this->error   = $this->throwable_to_wp_error( $e );
 		}
 
 		$default_timeout = 30.0;
@@ -358,8 +358,8 @@ public function __call( string $name, array $arguments ) {
 			}
 
 			return $result;
-		} catch ( Exception $e ) {
-			$this->error = $this->exception_to_wp_error( $e );
+		} catch ( Throwable $e ) {
+			$this->error = $this->throwable_to_wp_error( $e );
 
 			if ( self::is_generating_method( $name ) ) {
 				return $this->error;
@@ -369,33 +369,33 @@ public function __call( string $name, array $arguments ) {
 	}
 
 	/**
-	 * Converts an exception into a WP_Error with a structured error code and message.
+	 * Converts a throwable into a WP_Error with a structured error code and message.
 	 *
-	 * This method maps different exception types to specific WP_Error codes and HTTP status codes.
+	 * This method maps different throwable types to specific WP_Error codes and HTTP status codes.
 	 * The presence of the status codes means these WP_Error objects can be easily used in REST API responses
 	 * or other contexts where HTTP semantics are relevant.
 	 *
 	 * @since 7.0.0
 	 *
-	 * @param Exception $e The exception to convert.
+	 * @param Throwable $throwable The throwable to convert.
 	 * @return WP_Error The resulting WP_Error object.
 	 */
-	private function exception_to_wp_error( Exception $e ): WP_Error {
-		if ( $e instanceof NetworkException ) {
+	private function throwable_to_wp_error( Throwable $throwable ): WP_Error {
+		if ( $throwable instanceof NetworkException ) {
 			$error_code  = 'prompt_network_error';
 			$status_code = 503;
-		} elseif ( $e instanceof ClientException ) {
+		} elseif ( $throwable instanceof ClientException ) {
 			// `ClientException` uses HTTP status codes as exception codes, so we can rely on them.
 			$error_code  = 'prompt_client_error';
-			$status_code = $e->getCode() ? $e->getCode() : 400;
-		} elseif ( $e instanceof ServerException ) {
+			$status_code = $throwable->getCode() ? $throwable->getCode() : 400;
+		} elseif ( $throwable instanceof ServerException ) {
 			// `ServerException` uses HTTP status codes as exception codes, so we can rely on them.
 			$error_code  = 'prompt_upstream_server_error';
-			$status_code = $e->getCode() ? $e->getCode() : 500;
-		} elseif ( $e instanceof TokenLimitReachedException ) {
+			$status_code = $throwable->getCode() ? $throwable->getCode() : 500;
+		} elseif ( $throwable instanceof TokenLimitReachedException ) {
 			$error_code  = 'prompt_token_limit_reached';
 			$status_code = 400;
-		} elseif ( $e instanceof InvalidArgumentException ) {
+		} elseif ( $throwable instanceof InvalidArgumentException ) {
 			$error_code  = 'prompt_invalid_argument';
 			$status_code = 400;
 		} else {
@@ -405,10 +405,10 @@ private function exception_to_wp_error( Exception $e ): WP_Error {
 
 		return new WP_Error(
 			$error_code,
-			$e->getMessage(),
+			$throwable->getMessage(),
 			array(
 				'status'          => $status_code,
-				'exception_class' => get_class( $e ),
+				'exception_class' => get_class( $throwable ),
 			)
 		);
 	}
diff --git a/tests/phpunit/tests/ai-client/wpAiClientPromptBuilder.php b/tests/phpunit/tests/ai-client/wpAiClientPromptBuilder.php
index e758a6868aa42..31ab70485a565 100644
--- a/tests/phpunit/tests/ai-client/wpAiClientPromptBuilder.php
+++ b/tests/phpunit/tests/ai-client/wpAiClientPromptBuilder.php
@@ -2743,18 +2743,18 @@ public function test_exception_in_chained_method_caught_and_returned_by_terminat
 	}
 
 	/**
-	 * Invokes the private exception_to_wp_error method via reflection.
+	 * Invokes the private throwable_to_wp_error method via reflection.
 	 *
 	 * @param WP_AI_Client_Prompt_Builder $builder   The builder instance.
-	 * @param Exception                   $exception The exception to convert.
+	 * @param Throwable                   $throwable The throwable to convert.
 	 * @return WP_Error The resulting WP_Error.
 	 */
-	private function invoke_exception_to_wp_error( WP_AI_Client_Prompt_Builder $builder, Exception $exception ): WP_Error {
+	private function invoke_throwable_to_wp_error( WP_AI_Client_Prompt_Builder $builder, Throwable $throwable ): WP_Error {
 		$reflection = new ReflectionClass( WP_AI_Client_Prompt_Builder::class );
-		$method     = $reflection->getMethod( 'exception_to_wp_error' );
+		$method     = $reflection->getMethod( 'throwable_to_wp_error' );
 		self::set_accessible( $method );
 
-		return $method->invoke( $builder, $exception );
+		return $method->invoke( $builder, $throwable );
 	}
 
 	/**
@@ -2764,7 +2764,7 @@ private function invoke_exception_to_wp_error( WP_AI_Client_Prompt_Builder $buil
 	 */
 	public function test_exception_to_wp_error_network_exception() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new NetworkException( 'Connection timed out' )
 		);
@@ -2782,7 +2782,7 @@ public function test_exception_to_wp_error_network_exception() {
 	 */
 	public function test_exception_to_wp_error_client_exception_with_code() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new ClientException( 'Unauthorized', 401 )
 		);
@@ -2800,7 +2800,7 @@ public function test_exception_to_wp_error_client_exception_with_code() {
 	 */
 	public function test_exception_to_wp_error_client_exception_without_code() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new ClientException( 'Bad request' )
 		);
@@ -2817,7 +2817,7 @@ public function test_exception_to_wp_error_client_exception_without_code() {
 	 */
 	public function test_exception_to_wp_error_server_exception_with_code() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new ServerException( 'Bad gateway', 502 )
 		);
@@ -2835,7 +2835,7 @@ public function test_exception_to_wp_error_server_exception_with_code() {
 	 */
 	public function test_exception_to_wp_error_server_exception_without_code() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new ServerException( 'Internal server error' )
 		);
@@ -2852,7 +2852,7 @@ public function test_exception_to_wp_error_server_exception_without_code() {
 	 */
 	public function test_exception_to_wp_error_token_limit_reached_exception() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new TokenLimitReachedException( 'Token limit exceeded', 4096 )
 		);
@@ -2870,7 +2870,7 @@ public function test_exception_to_wp_error_token_limit_reached_exception() {
 	 */
 	public function test_exception_to_wp_error_invalid_argument_exception() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new AiClientInvalidArgumentException( 'Invalid model parameter' )
 		);
@@ -2888,7 +2888,7 @@ public function test_exception_to_wp_error_invalid_argument_exception() {
 	 */
 	public function test_exception_to_wp_error_generic_exception() {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error(
+		$error   = $this->invoke_throwable_to_wp_error(
 			$builder,
 			new Exception( 'Something went wrong' )
 		);
@@ -2899,6 +2899,51 @@ public function test_exception_to_wp_error_generic_exception() {
 		$this->assertSame( 'Exception', $error->get_error_data()['exception_class'] );
 	}
 
+	/**
+	 * Tests exception_to_wp_error maps an Error (e.g. TypeError) to a generic builder error.
+	 *
+	 * A TypeError extends Error, not Exception, so this guards against the
+	 * conversion only accepting Exception instances.
+	 *
+	 * @ticket 65505
+	 */
+	public function test_exception_to_wp_error_type_error() {
+		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
+		$error   = $this->invoke_throwable_to_wp_error(
+			$builder,
+			new TypeError( 'Argument must be of type float' )
+		);
+
+		$this->assertSame( 'prompt_builder_error', $error->get_error_code() );
+		$this->assertSame( 'Argument must be of type float', $error->get_error_message() );
+		$this->assertSame( 500, $error->get_error_data()['status'] );
+		$this->assertSame( 'TypeError', $error->get_error_data()['exception_class'] );
+	}
+
+	/**
+	 * Tests that a TypeError thrown by the wrapped SDK is caught and returned as a WP_Error.
+	 *
+	 * Passing an argument of the wrong type to a strict-typed SDK method throws a
+	 * TypeError (which extends Error, not Exception). The builder must catch it and
+	 * place itself in an error state instead of letting it fatal the request.
+	 *
+	 * @ticket 65505
+	 */
+	public function test_call_catches_type_error_from_invalid_argument_type() {
+		$builder = new WP_AI_Client_Prompt_Builder( $this->registry, 'Test prompt' );
+
+		// usingTemperature() expects a float; an array can never be coerced and throws a TypeError.
+		$result = $builder->using_temperature( array( 0.7 ) );
+
+		// The builder is returned (fluent interface preserved), now in an error state.
+		$this->assertInstanceOf( WP_AI_Client_Prompt_Builder::class, $result );
+
+		// A generating method now surfaces the stored WP_Error rather than fataling.
+		$error = $result->generate_text();
+		$this->assertWPError( $error );
+		$this->assertSame( 'prompt_builder_error', $error->get_error_code() );
+	}
+
 	/**
 	 * Tests exception_to_wp_error always includes status and exception_class in error data.
 	 *
@@ -2910,7 +2955,7 @@ public function test_exception_to_wp_error_generic_exception() {
 	 */
 	public function test_exception_to_wp_error_error_data_structure( Exception $exception ) {
 		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry() );
-		$error   = $this->invoke_exception_to_wp_error( $builder, $exception );
+		$error   = $this->invoke_throwable_to_wp_error( $builder, $exception );
 
 		$data = $error->get_error_data();
 		$this->assertIsArray( $data );