diff --git a/core/utils/dqm.py b/core/utils/dqm.py
index f4da920..09e202a 100644
--- a/core/utils/dqm.py
+++ b/core/utils/dqm.py
@@ -33,7 +33,7 @@ def list_certification_files(cert_type):
     url = "%s/%s/" % (dqm_cert_url, cert_type)
     page_content = requests.get(url=url, timeout=30)
     if page_content.status_code != 200:
-        error_msg = f"Unable to retrieve the content related to {cert_type}"
+        error_msg = "Unable to retrieve the content related to %s" % cert_type
         raise HTTPError(error_msg, response=page_content)
 
     # Parse the HTML and retrieve the file names
@@ -65,7 +65,7 @@ def get_certification_file(path):
     url = "%s/%s" % (dqm_cert_url, path)
     file = requests.get(url=url, timeout=30)
     if file.status_code != 200:
-        error_msg = f"Unable to retrieve the content related to {path}"
+        error_msg = "Unable to retrieve the content related to %s" % path
         raise HTTPError(error_msg, response=file)
 
     return file.json()
diff --git a/core/utils/run_the_matrix_pdmv.py b/core/utils/run_the_matrix_pdmv.py
index a1ec2eb..0b43cd2 100644
--- a/core/utils/run_the_matrix_pdmv.py
+++ b/core/utils/run_the_matrix_pdmv.py
@@ -4,6 +4,7 @@
 from __future__ import print_function
 
 import argparse
+import codecs
 import importlib
 import inspect
 import json
@@ -312,7 +313,7 @@ def main():
     print('All workflows:')
     print(json.dumps(workflows, indent=2, sort_keys=True))
     if opt.output_file:
-        with open(opt.output_file, 'w', encoding='utf-8') as workflows_file:
+        with codecs.open(opt.output_file, 'w', encoding='utf-8') as workflows_file:
             json.dump(workflows, workflows_file)