diff --git a/meshroom/aliceVision/KeyframeSelection.py b/meshroom/aliceVision/KeyframeSelection.py
index 6fb405774d..a28563d291 100644
--- a/meshroom/aliceVision/KeyframeSelection.py
+++ b/meshroom/aliceVision/KeyframeSelection.py
@@ -1,6 +1,7 @@
 __version__ = "5.0"
 
 from meshroom.core import desc
+from meshroom.core.desc.validators import success, error
 from meshroom.core.utils import EXR_STORAGE_DATA_TYPE, VERBOSE_LEVEL
 
 # List of supported video extensions (provided by OpenImageIO)
@@ -283,8 +284,9 @@ class KeyframeSelection(desc.AVCommandLineNode):
                         "For input videos, 'none' should not be used since the written keyframes are used to generate the output SfMData file.",
             value="none",
             values=["none", "exr", "jpg", "png"],
-            validValue=lambda node: not (any(ext in input.value.lower() for ext in videoExts for input in node.inputPaths.value) and node.outputExtension.value == "none"),
-            errorMessage="A video input has been provided. The output extension should be different from 'none'.",
+            validators=[
+                lambda node, _ : success() if not (any(ext in input.value.lower() for ext in videoExts for input in node.inputPaths.value) and node.outputExtension.value == "none") else error("A video input has been provided. The output extension should be different from 'none'.")
+            ],
         ),
         desc.ChoiceParam(
             name="storageDataType",
diff --git a/meshroom/aliceVision/LdrToHdrCalibration.py b/meshroom/aliceVision/LdrToHdrCalibration.py
index e125ee00b4..8d19753d93 100644
--- a/meshroom/aliceVision/LdrToHdrCalibration.py
+++ b/meshroom/aliceVision/LdrToHdrCalibration.py
@@ -4,6 +4,7 @@
 
 from meshroom.core import desc
 from meshroom.core.utils import COLORSPACES, VERBOSE_LEVEL
+from . ldrToHdrCommon import NbOfBracketsShouldBeAMultipleOfNbOfImages
 
 def findMetadata(d, keys, defaultValue):
     v = None
@@ -55,9 +56,8 @@ class LdrToHdrCalibration(desc.AVCommandLineNode):
             value=0,
             range=(0, 15, 1),
             invalidate=False,
-            group="user",  # not used directly on the command line
-            errorMessage="The set number of brackets is not a multiple of the number of input images.\n"
-                         "Errors will occur during the computation.",
+            group="user",  # not used directly on the command line,
+            validators=[NbOfBracketsShouldBeAMultipleOfNbOfImages()],
             exposed=True,
         ),
         desc.IntParam(
@@ -176,23 +176,15 @@ def update(cls, node):
         if "userNbBrackets" not in node.getAttributes().keys():
             # Old version of the node
             return
-        node.userNbBrackets.validValue = True  # Reset the status of "userNbBrackets"
 
         cameraInitOutput = node.input.getLinkParam(recursive=True)
         if not cameraInitOutput:
             node.nbBrackets.value = 0
             return
         if node.userNbBrackets.value != 0:
-            # The number of brackets has been manually forced: check whether it is valid or not
-            if cameraInitOutput and cameraInitOutput.node and cameraInitOutput.node.hasAttribute("viewpoints"):
-                viewpoints = cameraInitOutput.node.viewpoints.value
-                # The number of brackets should be a multiple of the number of input images
-                if (len(viewpoints) % node.userNbBrackets.value != 0):
-                    node.userNbBrackets.validValue = False
-                else:
-                    node.userNbBrackets.validValue = True
-            node.nbBrackets.value = node.userNbBrackets.value
-            return
+            if len(node.userNbBrackets.getErrorMessages()) > 0:
+                node.nbBrackets.value = node.userNbBrackets.value
+                return
 
         if not cameraInitOutput.node.hasAttribute("viewpoints"):
             if cameraInitOutput.node.hasAttribute("input"):
diff --git a/meshroom/aliceVision/LdrToHdrMerge.py b/meshroom/aliceVision/LdrToHdrMerge.py
index ba71e0e21b..8404c4f02d 100644
--- a/meshroom/aliceVision/LdrToHdrMerge.py
+++ b/meshroom/aliceVision/LdrToHdrMerge.py
@@ -4,6 +4,7 @@
 
 from meshroom.core import desc
 from meshroom.core.utils import COLORSPACES, EXR_STORAGE_DATA_TYPE, VERBOSE_LEVEL
+from . ldrToHdrCommon import NbOfBracketsShouldBeAMultipleOfNbOfImages
 
 def findMetadata(d, keys, defaultValue):
     v = None
@@ -55,8 +56,7 @@ class LdrToHdrMerge(desc.AVCommandLineNode):
             range=(0, 15, 1),
             invalidate=False,
             group="user",  # not used directly on the command line
-            errorMessage="The set number of brackets is not a multiple of the number of input images.\n"
-                         "Errors will occur during the computation.",
+            validators=[NbOfBracketsShouldBeAMultipleOfNbOfImages()],
             exposed=True,
         ),
         desc.IntParam(
@@ -249,23 +249,15 @@ def update(cls, node):
         if "userNbBrackets" not in node.getAttributes().keys():
             # Old version of the node
             return
-        node.userNbBrackets.validValue = True  # Reset the status of "userNbBrackets"
 
         cameraInitOutput = node.input.getLinkParam(recursive=True)
         if not cameraInitOutput:
             node.nbBrackets.value = 0
             return
         if node.userNbBrackets.value != 0:
-            # The number of brackets has been manually forced: check whether it is valid or not
-            if cameraInitOutput and cameraInitOutput.node and cameraInitOutput.node.hasAttribute("viewpoints"):
-                viewpoints = cameraInitOutput.node.viewpoints.value
-                # The number of brackets should be a multiple of the number of input images
-                if (len(viewpoints) % node.userNbBrackets.value != 0):
-                    node.userNbBrackets.validValue = False
-                else:
-                    node.userNbBrackets.validValue = True
-            node.nbBrackets.value = node.userNbBrackets.value
-            return
+           if len(node.userNbBrackets.getErrorMessages()) > 0:
+                node.nbBrackets.value = node.userNbBrackets.value
+                return
 
         if not cameraInitOutput.node.hasAttribute("viewpoints"):
             if cameraInitOutput.node.hasAttribute("input"):
diff --git a/meshroom/aliceVision/LdrToHdrSampling.py b/meshroom/aliceVision/LdrToHdrSampling.py
index fa88ccd3c8..6c8b3f35d0 100644
--- a/meshroom/aliceVision/LdrToHdrSampling.py
+++ b/meshroom/aliceVision/LdrToHdrSampling.py
@@ -4,6 +4,7 @@
 
 from meshroom.core import desc
 from meshroom.core.utils import COLORSPACES, VERBOSE_LEVEL
+from . ldrToHdrCommon import NbOfBracketsShouldBeAMultipleOfNbOfImages
 
 
 def findMetadata(d, keys, defaultValue):
@@ -71,8 +72,9 @@ class LdrToHdrSampling(desc.AVCommandLineNode):
             range=(0, 15, 1),
             invalidate=False,
             group="user",  # not used directly on the command line
-            errorMessage="The set number of brackets is not a multiple of the number of input images.\n"
-                         "Errors will occur during the computation.",
+            validators=[
+                NbOfBracketsShouldBeAMultipleOfNbOfImages()
+            ],
             exposed=True,
         ),
         desc.IntParam(
@@ -202,23 +204,16 @@ def update(cls, node):
             # Old version of the node
             return
         node.outliersNb = 0  # Reset the number of detected outliers
-        node.userNbBrackets.validValue = True  # Reset the status of "userNbBrackets"
 
         cameraInitOutput = node.input.getLinkParam(recursive=True)
         if not cameraInitOutput:
             node.nbBrackets.value = 0
             return
         if node.userNbBrackets.value != 0:
-            # The number of brackets has been manually forced: check whether it is valid or not
-            if cameraInitOutput and cameraInitOutput.node and cameraInitOutput.node.hasAttribute("viewpoints"):
-                viewpoints = cameraInitOutput.node.viewpoints.value
-                # The number of brackets should be a multiple of the number of input images
-                if (len(viewpoints) % node.userNbBrackets.value != 0):
-                    node.userNbBrackets.validValue = False
-                else:
-                    node.userNbBrackets.validValue = True
-            node.nbBrackets.value = node.userNbBrackets.value
-            return
+            
+            if len(node.userNbBrackets.getErrorMessages()) > 0:
+                node.nbBrackets.value = node.userNbBrackets.value
+                return
 
         if not cameraInitOutput.node.hasAttribute("viewpoints"):
             if cameraInitOutput.node.hasAttribute("input"):
diff --git a/meshroom/aliceVision/ldrToHdrCommon.py b/meshroom/aliceVision/ldrToHdrCommon.py
new file mode 100644
index 0000000000..7ce85036fb
--- /dev/null
+++ b/meshroom/aliceVision/ldrToHdrCommon.py
@@ -0,0 +1,27 @@
+from meshroom.core.attribute import Attribute
+from meshroom.core.node import Node
+from meshroom.core.desc.validators import AttributeValidator, success, error
+
+
+class NbOfBracketsShouldBeAMultipleOfNbOfImages(AttributeValidator):
+
+    def __call__(self, node: Node, attribute: Attribute):
+
+        if node.userNbBrackets.value == 0:
+            return success()
+
+        cameraInitOutput = node.input.getLinkParam(recursive=True)
+
+        # The number of brackets has been manually forced: check whether it is valid or not
+        if cameraInitOutput and cameraInitOutput.node and cameraInitOutput.node.hasAttribute("viewpoints"):
+            viewpoints = cameraInitOutput.node.viewpoints.value
+            # The number of brackets should be a multiple of the number of input images
+            if (len(viewpoints) % node.userNbBrackets.value != 0):
+                return error(
+                        "The set number of brackets is not a multiple of the number of input images.",
+                        "Errors will occur during the computation."
+                    )
+            else:
+                return success()
+
+        return success()