From f8115900215661e7284a51a3c23dda42a7e6b3e3 Mon Sep 17 00:00:00 2001
From: WithoutPants <53250216+WithoutPants@users.noreply.github.com>
Date: Thu, 27 Nov 2025 14:04:06 +1100
Subject: [PATCH] Debug log stderr when thumbnail generation fails

---
 internal/manager/task_generate_image_thumbnail.go | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/internal/manager/task_generate_image_thumbnail.go b/internal/manager/task_generate_image_thumbnail.go
index 2d32e2d60..14518d2bb 100644
--- a/internal/manager/task_generate_image_thumbnail.go
+++ b/internal/manager/task_generate_image_thumbnail.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"os/exec"
 
 	"github.com/stashapp/stash/pkg/fsutil"
 	"github.com/stashapp/stash/pkg/image"
@@ -20,6 +21,13 @@ func (t *GenerateImageThumbnailTask) GetDescription() string {
 	return fmt.Sprintf("Generating Thumbnail for image %s", t.Image.Path)
 }
 
+func (t *GenerateImageThumbnailTask) logStderr(err error) {
+	var exitErr *exec.ExitError
+	if errors.As(err, &exitErr) {
+		logger.Debugf("[generator] error output: %s", exitErr.Stderr)
+	}
+}
+
 func (t *GenerateImageThumbnailTask) Start(ctx context.Context) {
 	if !t.required() {
 		return
@@ -46,14 +54,15 @@ func (t *GenerateImageThumbnailTask) Start(ctx context.Context) {
 	if err != nil {
 		// don't log for animated images
 		if !errors.Is(err, image.ErrNotSupportedForThumbnail) {
-			logger.Errorf("[generator] getting thumbnail for image %s: %w", path, err)
+			logger.Errorf("[generator] getting thumbnail for image %s: %s", path, err.Error())
+			t.logStderr(err)
 		}
 		return
 	}
 
 	err = fsutil.WriteFile(thumbPath, data)
 	if err != nil {
-		logger.Errorf("[generator] writing thumbnail for image %s: %w", path, err)
+		logger.Errorf("[generator] writing thumbnail for image %s: %s", path, err.Error())
 		return
 	}
 }