Preserve actionable form errors

backend/src/test/java/fr/nessar/lmnporganizer/rental/application/lease/AmendLeaseServiceTest.java

@@ -316,14 +316,7 @@ private Lease activeLease() {
 
 private Tenant tenant(TenantId id, String firstName, String address) {
 	return new Tenant(
-		id,
+		id, LANDLORD_ID, firstName, "Martin", id.value() + "@example.com", "", address, List.of());
-		LANDLORD_ID,
-		firstName,
-		"Martin",
-		firstName.toLowerCase() + "@example.com",
-		"",
-		address,
-		List.of());
 }
 
 private RentDue due(YearMonth month) {

frontend/src/app/components/landlord-profile-completion-dialog/landlord-profile-completion-dialog.spec.ts

@@ -130,7 +130,7 @@ describe('LandlordProfileCompletionDialog', () => {
 		expect(fixture.nativeElement.textContent).toContain(
 			'Saisissez un numéro de téléphone valide.',
 		);
-		component.clearSaveFieldError('phone');
+		component.clearSaveFieldError('phoneValid');
 		fixture.detectChanges();
 
 		expect(fixture.nativeElement.textContent).not.toContain(

frontend/src/app/components/landlord-profile-form/landlord-profile-form.css

@@ -31,6 +31,13 @@
 	width: 100%;
 }
 
+.field-error {
+	display: block;
+	margin-top: -12px;
+	color: var(--danger);
+	font-size: 0.75rem;
+}
+
 .profile-actions {
 	display: flex;
 	flex-wrap: wrap;

frontend/src/app/components/landlord-profile-form/landlord-profile-form.html

@@ -21,7 +21,7 @@
 				autocomplete="given-name"
 			/>
 			@if (firstNameError()) {
-				<mat-error>{{ firstNameError() }}</mat-error>
+				<span class="field-error" role="alert">{{ firstNameError() }}</span>
 			}
 		</mat-form-field>
 		<mat-form-field appearance="outline"
@@ -34,7 +34,7 @@
 				autocomplete="family-name"
 			/>
 			@if (lastNameError()) {
-				<mat-error>{{ lastNameError() }}</mat-error>
+				<span class="field-error" role="alert">{{ lastNameError() }}</span>
 			}
 		</mat-form-field>
 		<mat-form-field appearance="outline"
@@ -48,7 +48,7 @@
 				autocomplete="email"
 			/>
 			@if (emailError()) {
-				<mat-error>{{ emailError() }}</mat-error>
+				<span class="field-error" role="alert">{{ emailError() }}</span>
 			}
 		</mat-form-field>
 		<mat-form-field appearance="outline"
@@ -62,7 +62,7 @@
 				autocomplete="tel"
 			/>
 			@if (phoneError()) {
-				<mat-error>{{ phoneError() }}</mat-error>
+				<span class="field-error" role="alert">{{ phoneError() }}</span>
 			}
 		</mat-form-field>
 		<mat-form-field appearance="outline" class="full-field"
@@ -75,7 +75,7 @@
 				autocomplete="street-address"
 			/>
 			@if (addressError()) {
-				<mat-error>{{ addressError() }}</mat-error>
+				<span class="field-error" role="alert">{{ addressError() }}</span>
 			}
 		</mat-form-field>
 	</fieldset>

frontend/src/app/components/landlord-profile-form/landlord-profile-form.spec.ts

@@ -22,7 +22,7 @@ describe('LandlordProfileForm', () => {
 
 		expect(saveRequested).not.toHaveBeenCalled();
 		expect(fixture.nativeElement.textContent).toContain(
-			'Veuillez renseigner tous les champs obligatoires.',
+			'Le numéro de téléphone est obligatoire.',
 		);
 	});
 
@@ -94,7 +94,6 @@ describe('LandlordProfileForm', () => {
 		]);
 		fixture.detectChanges();
 		await fixture.whenStable();
-
 		expect(fixture.nativeElement.textContent).toContain(
 			'Saisissez un numéro de téléphone valide.',
 		);
@@ -108,6 +107,7 @@ describe('LandlordProfileForm', () => {
 		phone.dispatchEvent(new Event('input'));
 
 		expect(changed).toHaveBeenCalledWith('phone');
+		expect(changed).toHaveBeenCalledWith('phoneValid');
 		fixture.componentRef.setInput('saveFieldErrors', [{ field: 'email', code: 'email' }]);
 		fixture.detectChanges();
 		await fixture.whenStable();

frontend/src/app/components/landlord-profile-form/landlord-profile-form.ts

@@ -17,6 +17,8 @@ const EMPTY_PROFILE: LandlordProfile = {
 	address: '',
 };
 
+type LandlordProfileField = keyof LandlordProfile | 'phoneValid';
+
 @Component({
 	selector: 'app-landlord-profile-form',
 	imports: [
@@ -38,7 +40,7 @@ export class LandlordProfileForm {
 	readonly saveError = input('');
 	readonly saveFieldErrors = input<FieldValidationError[]>([]);
 	readonly saveRequested = output<LandlordProfile>();
-	readonly fieldChanged = output<keyof LandlordProfile>();
+	readonly fieldChanged = output<LandlordProfileField>();
 	private previousServerErrorSignature = '';
 
 	readonly profileModel = signal<LandlordProfile>({ ...this.profile() });
@@ -93,6 +95,7 @@ export class LandlordProfileForm {
 	fieldWasChanged(field: keyof LandlordProfile): void {
 		this.validationError.set('');
 		this.fieldChanged.emit(field);
+		if (field === 'phone') this.fieldChanged.emit('phoneValid');
 	}
 
 	showSaveError(): boolean {
@@ -189,6 +192,7 @@ export class LandlordProfileForm {
 						: this.addressError()
 							? '#profile-address'
 							: '';
+		if (!selector) return;
 		const control = this.element.nativeElement.querySelector(selector);
 		if (control instanceof HTMLElement) control.focus();
 	}

frontend/src/app/components/lease-amendment-form/lease-amendment-form.spec.ts

@@ -36,6 +36,9 @@ describe('LeaseAmendmentForm', () => {
 			indexFlatRate: false,
 			status: 'ACTIVE',
 		});
+		const submitted = vi.fn();
+		fixture.componentInstance.submitted.subscribe(submitted);
+		fixture.detectChanges();
 		fixture.componentInstance.amendmentModel.update((model) => ({
 			...model,
 			effectiveDate: '2026-10-01',
@@ -43,9 +46,6 @@ describe('LeaseAmendmentForm', () => {
 			monthlyCharges: 0,
 			dueDay: 28,
 		}));
-		const submitted = vi.fn();
-		fixture.componentInstance.submitted.subscribe(submitted);
-		fixture.detectChanges();
 
 		fixture.componentInstance.save();
 
@@ -84,14 +84,14 @@ describe('LeaseAmendmentForm', () => {
 			indexFlatRate: false,
 			status: 'ACTIVE',
 		});
+		const submitted = vi.fn();
+		fixture.componentInstance.submitted.subscribe(submitted);
+		fixture.detectChanges();
 		fixture.componentInstance.amendmentModel.update((model) => ({
 			...model,
 			effectiveDate: '2026-10-01',
 			endDate: '2026-09-30',
 		}));
-		const submitted = vi.fn();
-		fixture.componentInstance.submitted.subscribe(submitted);
-		fixture.detectChanges();
 
 		fixture.componentInstance.save();
 

frontend/src/app/components/lease-end-page/lease-end-page.spec.ts

@@ -89,7 +89,7 @@ describe('LeaseEndPage', () => {
 		});
 	});
 
-	it('shows a skeleton, then a retryable load error', () => {
+	it('shows a skeleton, then a retryable safe load error', () => {
 		const response = new Subject<LeaseEndState>();
 		getState.mockReturnValueOnce(response);
 		const fixture = TestBed.createComponent(LeaseEndPage);
@@ -99,7 +99,10 @@ describe('LeaseEndPage', () => {
 
 		response.error({ error: { message: 'Bail introuvable' } });
 		fixture.detectChanges();
-		expect(fixture.nativeElement.textContent).toContain('Bail introuvable');
+		expect(fixture.nativeElement.textContent).toContain(
+			'Impossible de charger la fin de ce bail.',
+		);
+		expect(fixture.nativeElement.textContent).not.toContain('Bail introuvable');
 
 		getState.mockReturnValueOnce(of(state));
 		fixture.nativeElement.querySelector('.load-error button').click();
@@ -204,7 +207,7 @@ describe('LeaseEndPage', () => {
 		expect(fixture.nativeElement.textContent).toContain('Enregistrer l’accord');
 	});
 
-	it('keeps notice loading and failures local without publishing false success', () => {
+	it('keeps notice loading and safe failures local without publishing false success', () => {
 		getState.mockReturnValueOnce(of({ ...state, phase: 'ACTIVE', notices: [] }));
 		const response = new Subject<LeaseEndState>();
 		recordNotice.mockReturnValue(response);
@@ -228,7 +231,8 @@ describe('LeaseEndPage', () => {
 
 		response.error({ error: { message: 'Congé refusé' } });
 		fixture.detectChanges();
-		expect(fixture.nativeElement.textContent).toContain('Congé refusé');
+		expect(fixture.nativeElement.textContent).toContain('Impossible d’enregistrer ce congé.');
+		expect(fixture.nativeElement.textContent).not.toContain('Congé refusé');
 		expect(fixture.componentInstance.state()?.phase).toBe('ACTIVE');
 	});
 
@@ -278,7 +282,7 @@ describe('LeaseEndPage', () => {
 		expect(acceptWithdrawal).toHaveBeenCalledWith('lease-1', 'notice-1', request);
 	});
 
-	it('keeps a closure failure actionable', () => {
+	it('keeps a safe closure failure actionable', () => {
 		close.mockReturnValue(throwError(() => ({ error: { message: 'Clôture refusée' } })));
 		getState.mockReturnValueOnce(of({ ...state, phase: 'AWAITING_CLOSURE' }));
 		const fixture = TestBed.createComponent(LeaseEndPage);
@@ -290,7 +294,8 @@ describe('LeaseEndPage', () => {
 		});
 		fixture.detectChanges();
 
-		expect(fixture.nativeElement.textContent).toContain('Clôture refusée');
+		expect(fixture.nativeElement.textContent).toContain('Impossible de clôturer ce bail.');
+		expect(fixture.nativeElement.textContent).not.toContain('Clôture refusée');
 		expect(fixture.componentInstance.state()?.phase).toBe('AWAITING_CLOSURE');
 	});
 });

frontend/src/app/components/lease-form/lease-form.css

@@ -72,6 +72,11 @@
 .form-actions {
 	margin-top: 28px;
 }
+.core-field .field-error {
+	margin: -14px 0 0;
+	color: var(--danger);
+	font-size: 0.75rem;
+}
 @media (min-width: 700px) {
 	.three-columns {
 		grid-template-columns: repeat(3, minmax(0, 1fr));

frontend/src/app/components/lease-form/lease-form.html

@@ -38,7 +38,8 @@
 					</div>
 				</div>
 				<div class="form-grid">
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Appartement</mat-label
 						><mat-select
 							id="apartmentId"
@@ -50,11 +51,13 @@
 								<mat-option [value]="apartment.id">{{ apartment.name }}</mat-option>
 							}
 						</mat-select>
+						</mat-form-field>
 						@if (fieldError('apartmentId')) {
-							<mat-error>{{ fieldError('apartmentId') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('apartmentId') }}</p>
 						}
-					</mat-form-field>
+					</div>
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Locataires</mat-label
 						><mat-select
 							id="tenantIds"
@@ -68,10 +71,11 @@
 								>
 							}
 						</mat-select>
+						</mat-form-field>
 						@if (fieldError('tenantIds')) {
-							<mat-error>{{ fieldError('tenantIds') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('tenantIds') }}</p>
 						}
-					</mat-form-field>
+					</div>
 				</div>
 			</section>
 			<section class="form-section">
@@ -83,7 +87,8 @@
 					</div>
 				</div>
 				<div class="form-grid three-columns">
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Type de bail</mat-label
 						><mat-select
 							id="leaseType"
@@ -93,11 +98,13 @@
 							<mat-option value="STANDARD">Location meublée classique</mat-option>
 							<mat-option value="STUDENT">Location meublée étudiante</mat-option>
 						</mat-select>
+						</mat-form-field>
 						@if (fieldError('leaseType')) {
-							<mat-error>{{ fieldError('leaseType') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('leaseType') }}</p>
 						}
-					</mat-form-field>
+					</div>
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Date d'entrée</mat-label
 						><input
 							matInput
@@ -106,10 +113,11 @@
 							[formField]="leaseForm.startDate"
 							(change)="fieldWasChanged('startDate')"
 						/>
+						</mat-form-field>
 						@if (fieldError('startDate')) {
-							<mat-error>{{ fieldError('startDate') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('startDate') }}</p>
 						}
-					</mat-form-field>
+					</div>
 					<div class="lease-duration" aria-live="polite">
 						<span id="lease-end-date-label">Date de fin calculée</span>
 						<output aria-labelledby="lease-end-date-label">
@@ -120,7 +128,8 @@
 					@if (overlapWarning()) {
 						<p class="lease-warning" role="note">{{ overlapWarning() }}</p>
 					}
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Loyer mensuel</mat-label
 						><input
 							matInput
@@ -130,11 +139,13 @@
 							step="0.01"
 							(change)="fieldWasChanged('monthlyRent')"
 						/><span matTextSuffix>€</span>
+						</mat-form-field>
 						@if (fieldError('monthlyRent')) {
-							<mat-error>{{ fieldError('monthlyRent') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('monthlyRent') }}</p>
 						}
-					</mat-form-field>
+					</div>
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Charges mensuelles</mat-label
 						><input
 							matInput
@@ -144,11 +155,13 @@
 							step="0.01"
 							(change)="fieldWasChanged('monthlyCharges')"
 						/><span matTextSuffix>€</span>
+						</mat-form-field>
 						@if (fieldError('monthlyCharges')) {
-							<mat-error>{{ fieldError('monthlyCharges') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('monthlyCharges') }}</p>
 						}
-					</mat-form-field>
+					</div>
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Dépôt de garantie</mat-label
 						><input
 							matInput
@@ -158,11 +171,13 @@
 							step="0.01"
 							(change)="fieldWasChanged('securityDeposit')"
 						/><span matTextSuffix>€</span>
+						</mat-form-field>
 						@if (fieldError('securityDeposit')) {
-							<mat-error>{{ fieldError('securityDeposit') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('securityDeposit') }}</p>
 						}
-					</mat-form-field>
+					</div>
-					<mat-form-field appearance="outline"
+					<div class="core-field">
+						<mat-form-field appearance="outline"
 						><mat-label>Mode de récupération des charges</mat-label
 						><mat-select
 							id="chargeMethod"
@@ -185,10 +200,11 @@
 							step="1"
 							(change)="fieldWasChanged('dueDay')"
 						/><mat-hint>Entre le 1er et le 28 du mois</mat-hint>
+						</mat-form-field>
 						@if (fieldError('dueDay')) {
-							<mat-error>{{ fieldError('dueDay') }}</mat-error>
+							<p class="field-error" role="alert">{{ fieldError('dueDay') }}</p>
 						}
-					</mat-form-field>
+					</div>
 					@if (leaseModel().chargeMethod === 'FLAT_RATE') {
 						<mat-checkbox id="indexFlatRate" [formField]="leaseForm.indexFlatRate">
 							Indexer le forfait de charges avec le loyer

frontend/src/app/components/lease-form/lease-form.spec.ts

@@ -174,6 +174,7 @@ describe('LeaseForm', () => {
 		]);
 		fixture.detectChanges();
 		await new Promise<void>((resolve) => queueMicrotask(resolve));
+		fixture.detectChanges();
 
 		expect(fixture.componentInstance.leaseModel().monthlyCharges).toBe(50);
 		expect(fixture.nativeElement.textContent).toContain('charges mensuelles doivent être');
@@ -182,6 +183,7 @@ describe('LeaseForm', () => {
 		fixture.componentRef.setInput('saveFieldErrors', [{ field: 'dueDay', code: 'max' }]);
 		fixture.detectChanges();
 		await new Promise<void>((resolve) => queueMicrotask(resolve));
+		fixture.detectChanges();
 		expect(document.activeElement?.id).toBe('dueDay');
 	});
 

frontend/src/app/components/rent-payment-allocation-dialog/rent-payment-allocation-dialog.ts

@@ -19,7 +19,12 @@ import { RentDue } from '../../services/lease.service';
 import { saveFailure } from '../../services/http-error-message';
 import { formatEuro } from '../../services/rent-payment-format';
 import { RentPayment, RentPaymentService } from '../../services/rent-payment.service';
-import { isRentPaymentDataStale, RENT_PAYMENT_DATA_STALE } from '../rent-payment-dialog-result';
+import {
+	isRentPaymentConflict,
+	isRentPaymentDataStale,
+	RENT_PAYMENT_CONFLICT_MESSAGE,
+	RENT_PAYMENT_DATA_STALE,
+} from '../rent-payment-dialog-result';
 
 export interface EligibleRentDue {
 	rentDue: RentDue;
@@ -136,7 +141,13 @@ export class RentPaymentAllocationDialog {
 		const knownErrors = failure.fieldErrors.filter((fieldError) =>
 			this.isKnownFieldError(fieldError.field, fieldError.code),
 		);
-		this.error.set(knownErrors.length === failure.fieldErrors.length ? '' : failure.message);
+		this.error.set(
+			knownErrors.length > 0 && knownErrors.length === failure.fieldErrors.length
+				? ''
+				: isRentPaymentConflict(error)
+					? RENT_PAYMENT_CONFLICT_MESSAGE
+					: failure.message,
+		);
 		this.fieldErrorFields.set(new Set(knownErrors.map((fieldError) => fieldError.field)));
 		for (const fieldError of knownErrors) {
 			const control = this.form.get(fieldError.field);

frontend/src/app/components/rent-payment-dialog-result.ts

@@ -1,6 +1,8 @@
 import { RentPayment } from '../services/rent-payment.service';
 
 export const RENT_PAYMENT_DATA_STALE = 'RENT_PAYMENT_DATA_STALE';
+export const RENT_PAYMENT_CONFLICT_MESSAGE =
+	'Cette action n’est plus possible avec les données actuelles. Actualisez-les puis réessayez.';
 const CONCURRENT_CHANGE = 'concurrent_change';
 
 export type RentPaymentDialogResult = RentPayment | typeof RENT_PAYMENT_DATA_STALE;
@@ -18,3 +20,7 @@ export function isRentPaymentDataStale(error: unknown): boolean {
 		error.error.code === CONCURRENT_CHANGE
 	);
 }
+
+export function isRentPaymentConflict(error: unknown): boolean {
+	return typeof error === 'object' && error !== null && 'status' in error && error.status === 409;
+}

frontend/src/app/components/rent-payment-dialogs.spec.ts

@@ -2,7 +2,7 @@ import { Type } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
 import { MAT_DIALOG_DATA, MatDialogRef } from '@angular/material/dialog';
 import { of, throwError } from 'rxjs';
-import { RENT_PAYMENT_DATA_STALE } from './rent-payment-dialog-result';
+import { RENT_PAYMENT_CONFLICT_MESSAGE, RENT_PAYMENT_DATA_STALE } from './rent-payment-dialog-result';
 import { RentPaymentAllocationDialog } from './rent-payment-allocation-dialog/rent-payment-allocation-dialog';
 import { RentPaymentRefundDialog } from './rent-payment-refund-dialog/rent-payment-refund-dialog';
 import { RentPaymentReversalDialog } from './rent-payment-reversal-dialog/rent-payment-reversal-dialog';
@@ -80,10 +80,31 @@ describe('rent payment dialogs', () => {
 		component.submit();
 
 		expect(component.form.controls.amount.value).toBe(0.001);
-		expect(component.error()).toBe('Échéance déjà réglée');
+		expect(component.error()).toBe(RENT_PAYMENT_CONFLICT_MESSAGE);
 		expect(dialogRef.close).not.toHaveBeenCalled();
 	});
 
+	it('keeps non-concurrent conflicts visible for every payment action', () => {
+		payments.refund.mockReturnValue(throwError(() => ({ status: 409, error: { message: 'detail' } })));
+		const refund = create(RentPaymentRefundDialog, payment({ unallocatedBalance: 100 }));
+		refund.submit();
+		expect(refund.error()).toBe(RENT_PAYMENT_CONFLICT_MESSAGE);
+
+		payments.reverse.mockReturnValue(throwError(() => ({ status: 409, error: { message: 'detail' } })));
+		const reversal = create(RentPaymentReversalDialog, payment());
+		reversal.form.controls.reason.setValue('Erreur de saisie');
+		reversal.submit();
+		expect(reversal.error()).toBe(RENT_PAYMENT_CONFLICT_MESSAGE);
+
+		payments.allocate.mockReturnValue(throwError(() => ({ status: 409, error: { message: 'detail' } })));
+		const allocation = create(RentPaymentAllocationDialog, {
+			payment: payment({ unallocatedBalance: 100 }),
+			eligibleRentDues: [{ rentDue: due(), label: 'Juillet' }],
+		});
+		allocation.submit();
+		expect(allocation.error()).toBe(RENT_PAYMENT_CONFLICT_MESSAGE);
+	});
+
 	it('maps a known server field error and clears it when that field changes', () => {
 		payments.refund.mockReturnValue(
 			throwError(() => ({

frontend/src/app/components/rent-payment-refund-dialog/rent-payment-refund-dialog.ts

@@ -16,7 +16,12 @@ import { finalize } from 'rxjs';
 import { saveFailure } from '../../services/http-error-message';
 import { browserTimeZone, formatEuro, localIsoDate } from '../../services/rent-payment-format';
 import { RentPayment, RentPaymentService } from '../../services/rent-payment.service';
-import { isRentPaymentDataStale, RENT_PAYMENT_DATA_STALE } from '../rent-payment-dialog-result';
+import {
+	isRentPaymentConflict,
+	isRentPaymentDataStale,
+	RENT_PAYMENT_CONFLICT_MESSAGE,
+	RENT_PAYMENT_DATA_STALE,
+} from '../rent-payment-dialog-result';
 
 @Component({
 	selector: 'app-rent-payment-refund-dialog',
@@ -92,7 +97,13 @@ export class RentPaymentRefundDialog {
 		const knownErrors = failure.fieldErrors.filter((fieldError) =>
 			this.isKnownFieldError(fieldError.field, fieldError.code),
 		);
-		this.error.set(knownErrors.length === failure.fieldErrors.length ? '' : failure.message);
+		this.error.set(
+			knownErrors.length > 0 && knownErrors.length === failure.fieldErrors.length
+				? ''
+				: isRentPaymentConflict(error)
+					? RENT_PAYMENT_CONFLICT_MESSAGE
+					: failure.message,
+		);
 		this.fieldErrorFields.set(new Set(knownErrors.map((fieldError) => fieldError.field)));
 		for (const fieldError of knownErrors) {
 			const control = this.form.get(fieldError.field);

frontend/src/app/components/rent-payment-reversal-dialog/rent-payment-reversal-dialog.ts

@@ -15,7 +15,12 @@ import { finalize } from 'rxjs';
 import { saveFailure } from '../../services/http-error-message';
 import { browserTimeZone, formatEuro } from '../../services/rent-payment-format';
 import { RentPayment, RentPaymentService } from '../../services/rent-payment.service';
-import { isRentPaymentDataStale, RENT_PAYMENT_DATA_STALE } from '../rent-payment-dialog-result';
+import {
+	isRentPaymentConflict,
+	isRentPaymentDataStale,
+	RENT_PAYMENT_CONFLICT_MESSAGE,
+	RENT_PAYMENT_DATA_STALE,
+} from '../rent-payment-dialog-result';
 
 @Component({
 	selector: 'app-rent-payment-reversal-dialog',
@@ -87,7 +92,13 @@ export class RentPaymentReversalDialog {
 		const knownErrors = failure.fieldErrors.filter((fieldError) =>
 			this.isKnownFieldError(fieldError.field, fieldError.code),
 		);
-		this.error.set(knownErrors.length === failure.fieldErrors.length ? '' : failure.message);
+		this.error.set(
+			knownErrors.length > 0 && knownErrors.length === failure.fieldErrors.length
+				? ''
+				: isRentPaymentConflict(error)
+					? RENT_PAYMENT_CONFLICT_MESSAGE
+					: failure.message,
+		);
 		this.fieldErrorFields.set(new Set(knownErrors.map((fieldError) => fieldError.field)));
 		for (const fieldError of knownErrors) {
 			const control = this.form.get(fieldError.field);

frontend/src/app/components/rent-payment-validation-dialog/rent-payment-validation-dialog.ts

@@ -18,7 +18,12 @@ import { RentDue } from '../../services/lease.service';
 import { saveFailure } from '../../services/http-error-message';
 import { browserTimeZone, formatEuro, localIsoDate } from '../../services/rent-payment-format';
 import { RentPaymentService } from '../../services/rent-payment.service';
-import { isRentPaymentDataStale, RENT_PAYMENT_DATA_STALE } from '../rent-payment-dialog-result';
+import {
+	isRentPaymentConflict,
+	isRentPaymentDataStale,
+	RENT_PAYMENT_CONFLICT_MESSAGE,
+	RENT_PAYMENT_DATA_STALE,
+} from '../rent-payment-dialog-result';
 
 export interface RentPaymentValidationDialogData {
 	rentDue: RentDue;
@@ -109,7 +114,13 @@ export class RentPaymentValidationDialog {
 		const knownErrors = failure.fieldErrors.filter((fieldError) =>
 			this.isKnownFieldError(fieldError.field, fieldError.code),
 		);
-		this.error.set(knownErrors.length === failure.fieldErrors.length ? '' : failure.message);
+		this.error.set(
+			knownErrors.length > 0 && knownErrors.length === failure.fieldErrors.length
+				? ''
+				: isRentPaymentConflict(error)
+					? RENT_PAYMENT_CONFLICT_MESSAGE
+					: failure.message,
+		);
 		this.fieldErrorFields.set(new Set(knownErrors.map((fieldError) => fieldError.field)));
 		for (const fieldError of knownErrors) {
 			const control = this.form.get(fieldError.field);