diff --git a/odoo_openupgrade_wizard/tools/tools_docker.py b/odoo_openupgrade_wizard/tools/tools_docker.py
index ea12e16..21c4321 100644
--- a/odoo_openupgrade_wizard/tools/tools_docker.py
+++ b/odoo_openupgrade_wizard/tools/tools_docker.py
@@ -33,7 +33,7 @@ def build_image(path, tag, buildargs={}):
         )
         logger.debug("Image build done.")
     except docker.errors.BuildError as buildError:
-        logger.error("\n".join(buildError.build_log))
+        logger.error("\n".join([str(log) for log in buildError.build_log]))
         logger.error("Image build failed.")
 
     return image