diff --git a/packages/flutter_availability/lib/src/service/availability_service.dart b/packages/flutter_availability/lib/src/service/availability_service.dart
index 2449fa2..956d024 100644
--- a/packages/flutter_availability/lib/src/service/availability_service.dart
+++ b/packages/flutter_availability/lib/src/service/availability_service.dart
@@ -42,6 +42,8 @@ class AvailabilityService {
       userId: userId,
     );
 
+    availability.validate();
+
     await dataInterface.setAvailabilitiesForUser(
       userId: userId,
       availability: updatedAvailability,
@@ -163,6 +165,9 @@ class AvailabilityService {
     var updatedTemplate = template.copyWith(
       userId: userId,
     );
+
+    template.validate();
+
     await dataInterface.createTemplateForUser(
       userId,
       updatedTemplate,
@@ -171,6 +176,8 @@ class AvailabilityService {
 
   /// Updates a template
   Future<void> updateTemplate(AvailabilityTemplateModel template) async {
+    template.validate();
+
     await dataInterface.updateTemplateForUser(
       userId,
       template.id!,
diff --git a/packages/flutter_availability/lib/src/service/errors.dart b/packages/flutter_availability/lib/src/service/errors.dart
index 039f35c..cf005ce 100644
--- a/packages/flutter_availability/lib/src/service/errors.dart
+++ b/packages/flutter_availability/lib/src/service/errors.dart
@@ -1,8 +1,31 @@
 /// A set of errors
 enum AvailabilityError {
-  /// Error identifier when checking break mismatch
-  breakMismatchWithAvailability(
-    "The break needs to be within the timeframe of the availability",
+  /// Error identifier for when a submitted break ends before the availability
+  /// starts
+  breakEndBeforeStart(
+    "The break ends before the start of the break",
+  ),
+
+  /// Error identifier for when the submitted duration of a break is longer than
+  /// the difference between the start and end time
+  breakSubmittedDurationTooLong(
+    "The submitted duration is longer than the difference between the start "
+    "and end time",
+  ),
+
+  /// Error identifier for when the end of the day is before the start
+  endBeforeStart("The end of the day is before the start"),
+
+  /// Error identifier for when one of the submitted breaks starts before the
+  /// availability
+  templateBreakBeforeStart(
+    "One of the submitted breaks starts before the start of the availability",
+  ),
+
+  /// Error identifier for when one of the submitted breaks ends after the
+  /// availability
+  templateBreakAfterEnd(
+    "One of the submitted breaks ends after the end of the availability",
   );
 
   const AvailabilityError(this.description);
diff --git a/packages/flutter_availability/lib/src/ui/screens/availability_modification.dart b/packages/flutter_availability/lib/src/ui/screens/availability_modification.dart
index 84c476f..9af134c 100644
--- a/packages/flutter_availability/lib/src/ui/screens/availability_modification.dart
+++ b/packages/flutter_availability/lib/src/ui/screens/availability_modification.dart
@@ -1,4 +1,5 @@
 import "package:flutter/material.dart";
+import "package:flutter_availability/flutter_availability.dart";
 import "package:flutter_availability/src/service/availability_service.dart";
 import "package:flutter_availability/src/ui/view_models/availability_view_model.dart";
 import "package:flutter_availability/src/ui/view_models/break_view_model.dart";
@@ -8,7 +9,6 @@ import "package:flutter_availability/src/ui/widgets/availabillity_time_selection
 import "package:flutter_availability/src/ui/widgets/base_page.dart";
 import "package:flutter_availability/src/ui/widgets/pause_selection.dart";
 import "package:flutter_availability/src/util/scope.dart";
-import "package:flutter_availability_data_interface/flutter_availability_data_interface.dart";
 import "package:flutter_hooks/flutter_hooks.dart";
 
 /// Screen for modifying the availabilities for a specific daterange
@@ -78,18 +78,35 @@ class _AvailabilitiesModificationScreenState
         widget.onExit();
         return;
       }
-      if (_availabilityViewModel.templateSelected) {
-        await service.applyTemplate(
-          template: _availabilityViewModel.templates.first,
-          range: widget.dateRange,
-        );
-      } else {
-        await service.createAvailability(
-          availability: _availabilityViewModel.toModel(),
-          range: widget.dateRange,
+
+      AvailabilityError? error;
+      try {
+        if (_availabilityViewModel.templateSelected) {
+          await service.applyTemplate(
+            template: _availabilityViewModel.templates.first,
+            range: widget.dateRange,
+          );
+        } else {
+          await service.createAvailability(
+            availability: _availabilityViewModel.toModel(),
+            range: widget.dateRange,
+          );
+        }
+        widget.onExit();
+      } on AvailabilityEndBeforeStartException {
+        error = AvailabilityError.endBeforeStart;
+      } on BreakEndBeforeStartException {
+        error = AvailabilityError.breakEndBeforeStart;
+      } on BreakSubmittedDurationTooLongException {
+        error = AvailabilityError.breakSubmittedDurationTooLong;
+      }
+
+      if (error != null && context.mounted) {
+        await options.errorDisplayBuilder(
+          context,
+          error,
         );
       }
-      widget.onExit();
     }
 
     Future<void> onClickSave() async {
diff --git a/packages/flutter_availability/lib/src/ui/screens/template_day_modification.dart b/packages/flutter_availability/lib/src/ui/screens/template_day_modification.dart
index 91130b7..3839513 100644
--- a/packages/flutter_availability/lib/src/ui/screens/template_day_modification.dart
+++ b/packages/flutter_availability/lib/src/ui/screens/template_day_modification.dart
@@ -1,4 +1,5 @@
 import "package:flutter/material.dart";
+import "package:flutter_availability/src/service/errors.dart";
 import "package:flutter_availability/src/ui/view_models/day_template_view_model.dart";
 import "package:flutter_availability/src/ui/view_models/template_daydata_view_model.dart";
 import "package:flutter_availability/src/ui/widgets/base_page.dart";
@@ -70,12 +71,32 @@ class _DayTemplateModificationScreenState
 
     Future<void> onSavePressed() async {
       var template = _viewModel.toTemplate();
-      if (widget.template == null) {
-        await service.createTemplate(template);
-      } else {
-        await service.updateTemplate(template);
+      AvailabilityError? error;
+      try {
+        if (widget.template == null) {
+          await service.createTemplate(template);
+        } else {
+          await service.updateTemplate(template);
+        }
+        widget.onExit();
+      } on BreakEndBeforeStartException {
+        error = AvailabilityError.breakEndBeforeStart;
+      } on BreakSubmittedDurationTooLongException {
+        error = AvailabilityError.breakSubmittedDurationTooLong;
+      } on TemplateEndBeforeStartException {
+        error = AvailabilityError.endBeforeStart;
+      } on TemplateBreakBeforeStartException {
+        error = AvailabilityError.templateBreakBeforeStart;
+      } on TemplateBreakAfterEndException {
+        error = AvailabilityError.templateBreakAfterEnd;
+      }
+
+      if (error != null && context.mounted) {
+        await options.errorDisplayBuilder(
+          context,
+          error,
+        );
       }
-      widget.onExit();
     }
 
     var canSave = _viewModel.canSave;
diff --git a/packages/flutter_availability/lib/src/ui/widgets/defaults/default_error_display.dart b/packages/flutter_availability/lib/src/ui/widgets/defaults/default_error_display.dart
index 0689244..839a8b7 100644
--- a/packages/flutter_availability/lib/src/ui/widgets/defaults/default_error_display.dart
+++ b/packages/flutter_availability/lib/src/ui/widgets/defaults/default_error_display.dart
@@ -23,11 +23,13 @@ class DefaultErrorDisplayDialog extends StatelessWidget {
   }
 
   @override
-  Widget build(BuildContext context) => Column(
-        children: [
-          Text(_error.name),
-          const SizedBox(height: 20),
-          Text(_error.description),
-        ],
+  Widget build(BuildContext context) => Scaffold(
+        body: Column(
+          children: [
+            Text(_error.name),
+            const SizedBox(height: 20),
+            Text(_error.description),
+          ],
+        ),
       );
 }
diff --git a/packages/flutter_availability_data_interface/lib/src/models/availability.dart b/packages/flutter_availability_data_interface/lib/src/models/availability.dart
index 83e2dd7..0567905 100644
--- a/packages/flutter_availability_data_interface/lib/src/models/availability.dart
+++ b/packages/flutter_availability_data_interface/lib/src/models/availability.dart
@@ -1,6 +1,16 @@
 // ignore_for_file: Generated using data class generator
 import "package:flutter_availability_data_interface/src/utils.dart";
 
+/// Exception thrown when the end is before the start
+class BreakEndBeforeStartException implements Exception {}
+
+/// Exception thrown when the submitted duration is longer than the difference
+/// between the start and end time
+class BreakSubmittedDurationTooLongException implements Exception {}
+
+/// Exception thrown when the end is before the start
+class AvailabilityEndBeforeStartException implements Exception {}
+
 /// A model defining the data structure for an availability
 class AvailabilityModel {
   /// Creates a new availability
@@ -81,6 +91,17 @@ class AvailabilityModel {
     }
     return true;
   }
+
+  /// Verify the validity of this availability
+  void validate() {
+    if (startDate.compareTo(endDate) < 0) {
+      throw AvailabilityEndBeforeStartException();
+    }
+
+    for (var breakData in breaks) {
+      breakData.validate();
+    }
+  }
 }
 
 /// A model defining the structure of a break within an [AvailabilityModel]
@@ -177,4 +198,19 @@ class AvailabilityBreakModel {
       endTime.hour == other.endTime.hour &&
       endTime.minute == other.endTime.minute &&
       submittedDuration == other.submittedDuration;
+
+  /// Verify the validity of this break
+  void validate() {
+    if (endTime.compareTo(startTime) < 0) {
+      throw BreakEndBeforeStartException();
+    }
+
+    if (submittedDuration != null) {
+      var calculatedDuration = endTime.difference(startTime);
+
+      if (calculatedDuration < submittedDuration!) {
+        throw BreakSubmittedDurationTooLongException();
+      }
+    }
+  }
 }
diff --git a/packages/flutter_availability_data_interface/lib/src/models/templates.dart b/packages/flutter_availability_data_interface/lib/src/models/templates.dart
index 2283b42..d8e0662 100644
--- a/packages/flutter_availability_data_interface/lib/src/models/templates.dart
+++ b/packages/flutter_availability_data_interface/lib/src/models/templates.dart
@@ -1,6 +1,17 @@
 import "package:flutter_availability_data_interface/flutter_availability_data_interface.dart";
 import "package:flutter_availability_data_interface/src/models/availability.dart";
 
+/// Exception thrown when the end is before the start
+class TemplateEndBeforeStartException implements Exception {}
+
+/// Exception thrown when the start of a break is before the start of the
+/// availability
+class TemplateBreakBeforeStartException implements Exception {}
+
+/// Exception thrown when the end of a break is after the end of the
+/// availability
+class TemplateBreakAfterEndException implements Exception {}
+
 /// A limited set of different availability template types
 enum AvailabilityTemplateType {
   /// A template that applies to any day, regardless of when it is.
@@ -103,6 +114,11 @@ class AvailabilityTemplateModel {
   /// Get the end time for the specified day in the week for this template
   DateTime? getEndTimeForDayOfWeek(WeekDay weekDay) =>
       templateData.getEndTimeForDayOfWeek(weekDay);
+
+  /// Verify the validity of this template
+  void validate() {
+    templateData.validate();
+  }
 }
 
 /// Used as the key for defining week-based templates
@@ -167,6 +183,9 @@ abstract interface class TemplateData {
 
   /// Get the end time for the specified day in the week for this template
   DateTime? getEndTimeForDayOfWeek(WeekDay weekDay);
+
+  /// Verify the validity of the data in this template
+  void validate();
 }
 
 /// A week based template data structure
@@ -261,6 +280,13 @@ class WeekTemplateData implements TemplateData {
   /// Get the end time for the specified day in the week for this template
   @override
   DateTime? getEndTimeForDayOfWeek(WeekDay weekDay) => _data[weekDay]?.endTime;
+
+  @override
+  void validate() {
+    for (var dayData in _data.entries) {
+      dayData.value.validate();
+    }
+  }
 }
 
 /// A day based template data structure
@@ -371,6 +397,25 @@ class DayTemplateData implements TemplateData {
   /// Get the end time for the specified day in the week for this template
   @override
   DateTime? getEndTimeForDayOfWeek(WeekDay weekDay) => endTime;
+
+  @override
+  void validate() {
+    if (endTime.compareTo(startTime) < 0) {
+      throw TemplateEndBeforeStartException();
+    }
+
+    for (var breakData in breaks) {
+      breakData.validate();
+
+      if (breakData.startTime.compareTo(startTime) < 0) {
+        throw TemplateBreakBeforeStartException();
+      }
+
+      if (breakData.endTime.compareTo(endTime) > 0) {
+        throw TemplateBreakAfterEndException();
+      }
+    }
+  }
 }
 
 List<DateTime> _getDatesBetween(DateTime startDate, DateTime endDate) {