diff --git a/src/synthesis_workflow/validation.py b/src/synthesis_workflow/validation.py
index 6e2a919..903522b 100644
--- a/src/synthesis_workflow/validation.py
+++ b/src/synthesis_workflow/validation.py
@@ -1058,6 +1058,8 @@ def build_file_list(df, mtypes, path_col):
         with DisableLogger():
             pdf.savefig(fig, bbox_inches="tight", dpi=dpi)
         plt.close(fig)
+    if not Path(output_path).exists():
+        raise Exception(output_path)
 
 
 def extract_angle_data(df, morph_key, pia=None):