diff --git a/cocluto/quman.py b/cocluto/quman.py
index e34e29a..be59e80 100755
--- a/cocluto/quman.py
+++ b/cocluto/quman.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 from abc import ABC, abstractmethod
+import sys
 from typing import List, Dict, Any, Union
 import logging
 import subprocess
@@ -81,6 +82,12 @@ class Sge(IGridEngine):
 
     def __init__(self, dry_run: bool = False):
         self.dry_run = dry_run
+        if not self.dry_run:
+            # check that qmod command is available
+            try:
+                subprocess.run(["qmod", "-h"], check=True, capture_output=True)
+            except FileNotFoundError:
+                raise RuntimeError("qmod command not found. Please make sure that the grid engine client is installed and qmod command is available in the PATH.")
 
     def run_qmod(self, args):
         """runs qmod with the given arguments."""
@@ -88,7 +95,10 @@ class Sge(IGridEngine):
         if self.dry_run:
             print(f"Dry run: {' '.join(cmd)}")
         else:
-            subprocess.run(cmd, check=True)
+            try:
+                subprocess.run(cmd, check=True)
+            except subprocess.CalledProcessError as e:
+                raise RuntimeError(f"qmod command failed: {e}")
 
     def disable_queue_machine(self, queue_machine: QueueMachineId):
         self.run_qmod(["-d", queue_machine])
@@ -188,8 +198,10 @@ class QueueManager:
     db_backend: ISqlDatabaseBackend
     grid_engine: IGridEngine
 
-    def __init__(self, db_backend: ISqlDatabaseBackend, grid_engine: IGridEngine = Sge()):
+    def __init__(self, db_backend: ISqlDatabaseBackend, grid_engine: IGridEngine = None):
         self.db_backend = db_backend
+        if grid_engine is None:
+            grid_engine = Sge()
         self.grid_engine = grid_engine
 
     def log_modification(self, queue_machines: List[QueueMachineId], action: str, disable_tag: DisableTag, reason: str) -> LogId:
@@ -318,23 +330,27 @@ class QueueManager:
 
 def main():
 
-    parser = argparse.ArgumentParser(description="qmod wrapper to manage queue states with a counter and logging.", epilog="Example usage: quman d main.q --disable-tag admin.graffy.bug4242 --reason 'preparing cluster to shutdown for power shortage, see bug 4242'")
-    parser.add_argument("action", choices=["d", "e"], help="Action: d (deactivate) or e (activate)")
-    parser.add_argument("queue", help="Queue to modify (e.g., main.q@node42@univ-rennes.fr, main.q, etc.)")
-    parser.add_argument("--reason", required=True, help="Reason for the deactivation/activation")
-    parser.add_argument("--disable-tag", required=True, help="tag for the disable request (e.g., auto.croconaus, manual.graffy, etc.)")
-    args = parser.parse_args()
+    try:
+        parser = argparse.ArgumentParser(description="qmod wrapper to manage queue states with a counter and logging.", epilog="Example usage: quman d main.q --disable-tag admin.graffy.bug4242 --reason 'preparing cluster to shutdown for power shortage, see bug 4242'")
+        parser.add_argument("action", choices=["d", "e"], help="Action: d (deactivate) or e (activate)")
+        parser.add_argument("queue", help="Queue to modify (e.g., main.q@node42@univ-rennes.fr, main.q, etc.)")
+        parser.add_argument("--reason", required=True, help="Reason for the deactivation/activation")
+        parser.add_argument("--disable-tag", required=True, help="tag for the disable request (e.g., auto.croconaus, manual.graffy, etc.)")
+        args = parser.parse_args()
 
-    db_backend = create_db_backend()
-    quman = QueueManager(db_backend, Sge(dry_run=False))  # set dry_run to False to actually run qmod commands
+        db_backend = create_db_backend()
+        quman = QueueManager(db_backend, Sge(dry_run=False))  # set dry_run to False to actually run qmod commands
 
-    quman.synchronize_with_grid_engine()
-    queue_machines = quman.get_queue_machines(args.queue)
+        quman.synchronize_with_grid_engine()
+        queue_machines = quman.get_queue_machines(args.queue)
 
-    if args.action == "d":
-        quman.request_queue_machines_deactivation(queue_machines, args.disable_tag, args.reason)
-    elif args.action == "e":
-        quman.request_queue_machines_activation(queue_machines, args.disable_tag, args.reason)
+        if args.action == "d":
+            quman.request_queue_machines_deactivation(queue_machines, args.disable_tag, args.reason)
+        elif args.action == "e":
+            quman.request_queue_machines_activation(queue_machines, args.disable_tag, args.reason)
+    except RuntimeError as e:
+        sys.stderr.write(f"An error occurred: {e}\n")
+        exit(1)
 
 
 if __name__ == "__main__":
diff --git a/cocluto/version.py b/cocluto/version.py
index a3afd0e..cf9f82c 100644
--- a/cocluto/version.py
+++ b/cocluto/version.py
@@ -1,4 +1,4 @@
-__version__ = '1.0.14'
+__version__ = '1.0.15'
 
 
 class Version(object):