diff --git a/app/models/user_working_hours.rb b/app/models/user_working_hours.rb
index 013db8c2eff3..922d0c132600 100644
--- a/app/models/user_working_hours.rb
+++ b/app/models/user_working_hours.rb
@@ -38,14 +38,12 @@ class UserWorkingHours < ApplicationRecord
   belongs_to :user, inverse_of: :working_hours
 
   validates :valid_from, presence: true, uniqueness: { scope: :user_id }
-  validates :monday_hours, :tuesday_hours, :wednesday_hours, :thursday_hours, :friday_hours, :saturday_hours, :sunday_hours,
-            presence: true,
-            numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: 24 }
   validates :availability_factor,
             presence: true,
             numericality: { only_integer: true, greater_than_or_equal_to: 0, less_than_or_equal_to: 100 }
 
   validate :at_least_one_working_day_selected
+  validate :working_day_hours_present_and_in_range
 
   scope :for_user, ->(user) { where(user:) }
 
@@ -72,7 +70,7 @@ def self.current
 
   DAYS.each do |day|
     define_method("#{day}_hours") do
-      (public_send(day) / 60.0).round(2)
+      ((public_send(day) || 0) / 60.0).round(2)
     end
 
     define_method("#{day}_hours=") do |value|
@@ -158,8 +156,21 @@ def abbr_day_name(day)
   end
 
   def at_least_one_working_day_selected
-    if DAYS.all? { |day| public_send(day).zero? }
+    if DAYS.all? { |day| public_send(day).to_i.zero? }
       errors.add(:days, :no_working_day)
     end
   end
+
+  def working_day_hours_present_and_in_range
+    DAYS.each do |day|
+      minutes = public_send(day)
+      attr = :"#{day}_hours"
+
+      if minutes.nil?
+        errors.add(attr, :blank)
+      elsif minutes.negative? || minutes > 24 * 60
+        errors.add(attr, :less_than_or_equal_to, count: 24)
+      end
+    end
+  end
 end
diff --git a/spec/models/user_working_hours_spec.rb b/spec/models/user_working_hours_spec.rb
index e5b1c5a42c7e..55bb86720233 100644
--- a/spec/models/user_working_hours_spec.rb
+++ b/spec/models/user_working_hours_spec.rb
@@ -74,6 +74,26 @@
                                                                        .is_greater_than_or_equal_to(0)
                                                                        .is_less_than_or_equal_to(100)
     end
+
+    describe "with a nil weekday column (e.g. omitted from a create payload)" do
+      it "is invalid rather than raising when a single weekday is nil" do
+        subject.public_send(:wednesday=, nil)
+
+        expect { subject.valid? }.not_to raise_error
+        expect(subject).not_to be_valid
+        expect(subject.errors[:wednesday_hours]).to be_present
+      end
+
+      it "is invalid rather than raising when every weekday is nil" do
+        %i[monday tuesday wednesday thursday friday saturday sunday].each do |day|
+          subject.public_send(:"#{day}=", nil)
+        end
+
+        expect { subject.valid? }.not_to raise_error
+        expect(subject).not_to be_valid
+        expect(subject.errors[:days]).to be_present
+      end
+    end
   end
 
   describe "hours accessors" do
@@ -85,6 +105,11 @@
           working_hours.public_send("#{day}=", 150)
           expect(working_hours.public_send("#{day}_hours")).to eq(2.5)
         end
+
+        it "returns 0.0 rather than raising when the underlying minutes column is nil" do
+          working_hours.public_send("#{day}=", nil)
+          expect(working_hours.public_send("#{day}_hours")).to eq(0.0)
+        end
       end
 
       describe "##{day}_hours=" do