diff --git a/src/DIRAC/Core/Utilities/File.py b/src/DIRAC/Core/Utilities/File.py
index 9548faea8a6..2141eaa041f 100755
--- a/src/DIRAC/Core/Utilities/File.py
+++ b/src/DIRAC/Core/Utilities/File.py
@@ -4,15 +4,16 @@
    By default on Error they return None.
 """
 
-import os
+import errno
+import glob
 import hashlib
+import os
 import random
-import glob
-import sys
 import re
-import errno
 import stat
+import sys
 import tempfile
+import threading
 from contextlib import contextmanager
 
 # Translation table of a given unit to Bytes
@@ -277,6 +278,32 @@ def secureOpenForWrite(filename=None, *, text=True):
         yield fd, filename
 
 
+def safe_listdir(directory, timeout=60):
+    """This is a "safe" list directory,
+    for lazily-loaded File Systems like CVMFS.
+    There's by default a 60 seconds timeout.
+
+    :param str directory: directory to list
+    :param int timeout: optional timeout, in seconds. Defaults to 60.
+    """
+
+    def listdir(directory):
+        try:
+            return os.listdir(directory)
+        except FileNotFoundError:
+            print(f"{directory} not found")
+            return []
+
+    contents = []
+    t = threading.Thread(target=lambda: contents.extend(listdir(directory)))
+    t.daemon = True  # don't delay program's exit
+    t.start()
+    t.join(timeout)
+    if t.is_alive():
+        return None  # timeout
+    return contents
+
+
 if __name__ == "__main__":
     for p in sys.argv[1:]:
         print(f"{p} : {getGlobbedTotalSize(p)} bytes")
diff --git a/src/DIRAC/Core/Utilities/Os.py b/src/DIRAC/Core/Utilities/Os.py
index 103d0676575..45d431c2b47 100755
--- a/src/DIRAC/Core/Utilities/Os.py
+++ b/src/DIRAC/Core/Utilities/Os.py
@@ -3,12 +3,14 @@
    by default on Error they return None
 """
 import os
+import platform
 import shutil
 
 import DIRAC
+from DIRAC.Core.Utilities import List
 from DIRAC.Core.Utilities.Decorators import deprecated
+from DIRAC.Core.Utilities.File import safe_listdir
 from DIRAC.Core.Utilities.Subprocess import shellCall, systemCall
-from DIRAC.Core.Utilities import List
 
 DEBUG = 0
 
@@ -150,3 +152,26 @@ def sourceEnv(timeout, cmdTuple, inputEnv=None):
 @deprecated("Will be removed in DIRAC 8.1", onlyOnce=True)
 def which(executable):
     return shutil.which(executable)
+
+
+def findImage(operating_system="alma9"):
+    """Finds the image for the current platform"""
+    from DIRAC.ConfigurationSystem.Client.Helpers.Operations import Operations
+
+    plat = DIRAC.gConfig.getValue("LocalSite/Platform", platform.machine())
+    if plat == "x86_64":
+        plat = "amd64"
+
+    CVMFS_locations = DIRAC.gConfig.getValue(
+        "LocalSite/CVMFS_locations", Operations().getValue("Pilot/CVMFS_locations", [])
+    )
+
+    rootImage = None
+
+    for candidate in CVMFS_locations:
+        rootImage = os.path.join(candidate, "containers", "os-base", f"{operating_system}-devel", "prod", plat)
+        DIRAC.gLogger.verbose(f"Checking {rootImage} existence")
+        if safe_listdir(rootImage):
+            break
+
+    return rootImage
diff --git a/src/DIRAC/Resources/Computing/SingularityComputingElement.py b/src/DIRAC/Resources/Computing/SingularityComputingElement.py
index f0e153d11b4..e0ce4d185e8 100644
--- a/src/DIRAC/Resources/Computing/SingularityComputingElement.py
+++ b/src/DIRAC/Resources/Computing/SingularityComputingElement.py
@@ -11,8 +11,6 @@
     See the Configuration/Resources/Computing documention for details on
     where to set the option parameters.
 """
-
-import io
 import json
 import os
 import re
@@ -21,7 +19,8 @@
 import tempfile
 
 import DIRAC
-from DIRAC import S_OK, S_ERROR, gConfig, gLogger
+from DIRAC import S_ERROR, S_OK, gConfig, gLogger
+from DIRAC.Core.Utilities.Os import findImage
 from DIRAC.Core.Utilities.Subprocess import systemCall
 from DIRAC.ConfigurationSystem.Client.Helpers import Operations
 from DIRAC.Core.Utilities.ThreadScheduler import gThreadScheduler
@@ -31,6 +30,7 @@
 
 # Default container to use if it isn't specified in the CE options
 CONTAINER_DEFROOT = "/cvmfs/cernvm-prod.cern.ch/cvm4"
+OPERATING_SYSTEM = "alma9"
 CONTAINER_WORKDIR = "DIRAC_containers"
 CONTAINER_INNERDIR = "/tmp"
 
@@ -107,9 +107,6 @@ def __init__(self, ceUniqueID):
         super().__init__(ceUniqueID)
         self.__submittedJobs = 0
         self.__runningJobs = 0
-        self.__root = CONTAINER_DEFROOT
-        if "ContainerRoot" in self.ceParameters:
-            self.__root = self.ceParameters["ContainerRoot"]
         self.__workdir = CONTAINER_WORKDIR
         self.__innerdir = CONTAINER_INNERDIR
         self.__singularityBin = "singularity"
@@ -147,7 +144,7 @@ def __hasSingularity(self):
                 self.log.debug(f'Use singularity from "{self.__singularityBin}"')
                 return True
         if "PATH" not in os.environ:
-            return False  # Hmm, PATH not set? How unusual...
+            return False  # PATH might not be set (e.g. HTCondorCE)
         searchPaths = os.environ["PATH"].split(os.pathsep)
         # We can use CVMFS as a last resort if userNS is enabled
         if self.__hasUserNS():
@@ -359,8 +356,6 @@ def submitJob(self, executableFile, proxy=None, **kwargs):
 
         :return: S_OK(payload exit code) / S_ERROR() if submission issue
         """
-        rootImage = self.__root
-        renewTask = None
         # Check that singularity is available
         if not self.__hasSingularity():
             self.log.error("Singularity is not installed on PATH.")
@@ -375,6 +370,7 @@ def submitJob(self, executableFile, proxy=None, **kwargs):
         baseDir = ret["baseDir"]
         tmpDir = ret["tmpDir"]
 
+        renewTask = False
         if proxy:
             payloadProxyLoc = ret["proxyLocation"]
 
@@ -449,6 +445,9 @@ def submitJob(self, executableFile, proxy=None, **kwargs):
             containerOpts = self.ceParameters["ContainerOptions"].split(",")
             for opt in containerOpts:
                 cmd.extend([opt.strip()])
+
+        rootImage = findImage() or self.ceParameters.get("ContainerRoot") or CONTAINER_DEFROOT
+
         if os.path.isdir(rootImage) or os.path.isfile(rootImage):
             cmd.extend([rootImage, innerCmd])
         else: