diff --git a/docs/changelog.md b/docs/changelog.md
index 73e5dc24d456087bb32fcdbbec1796b936b477f3..24a8d1cafe6aab804cfa7ccb68d6c8e487684cd5 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -8,3 +8,11 @@ Additonally, setting of the THERMOGIS_JAR and JAVA_HOME environment variables ca
 This is particularly useful for users who do not have admin rights.
 
 We also recognise that having to replace the Jar file everytime we update it is clunky and we will be working hard to remove this necessity in future updates.
+
+## v1.2.1 (21-11-2025)
+Fixing a bug caused by the update in the Jar file. calculateDoubletPerformance in the Java source code returns Null if one of the optimizers failed. 
+Pythermogis was still expecting a DoubletOutput class with all values set to -9999 in case of optimizer failure. 
+
+Additionally:
+    - two functions have been added to print out the environment variables THERMOGIS_JAR and JAVA_HOME. This enables users to debug if their are issues with their installation
+
diff --git a/pixi.lock b/pixi.lock
index 0f624af11f635a8bc949d06af2a35a9f94b3aa63..b3ca5554899697e34e7eff5bac6c361dee0ddc9b 100644
--- a/pixi.lock
+++ b/pixi.lock
@@ -4829,8 +4829,8 @@ packages:
   timestamp: 1740946648058
 - pypi: ./
   name: pythermogis
-  version: 1.2.0
-  sha256: 50c9d857c9314b246b28d7e610647475414c718d839408818aa4f441813b51a7
+  version: 1.2.1
+  sha256: 0ae9336fdba95931a8e5b2b0ce4a61acd3bcd3c3d685b2292b11e436d43245b0
   requires_dist:
   - jpype1>=1.5.2,<2
   - xarray==2024.9.0.*
diff --git a/pyproject.toml b/pyproject.toml
index 73e4690a10237544fccf468b68b6b676cf48ae6f..0d02ebf473306311ffbd3c57a294d9a5e8da7f23 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pythermogis"
-version = "1.2.0"
+version = "1.2.1"
 description = "This repository is used as a python API for the ThermoGIS Doublet simulations"
 authors = [
     { name = "Hen Brett", email = "hen.brett@tno.nl" },