diff --git a/dmp-backend/core/src/main/java/eu/eudat/commons/enums/FieldType.java b/dmp-backend/core/src/main/java/eu/eudat/commons/enums/FieldType.java
index 97324ed53..9217180f4 100644
--- a/dmp-backend/core/src/main/java/eu/eudat/commons/enums/FieldType.java
+++ b/dmp-backend/core/src/main/java/eu/eudat/commons/enums/FieldType.java
@@ -96,7 +96,8 @@ public enum FieldType implements DatabaseEnum<String> {
 	public static boolean isTextType(FieldType fieldType){
 		return  fieldType.equals(FieldType.FREE_TEXT) || fieldType.equals(FieldType.CHECK_BOX) || fieldType.equals(FieldType.TEXT_AREA) ||
 				fieldType.equals(FieldType.RICH_TEXT_AREA) || fieldType.equals(FieldType.UPLOAD) || fieldType.equals(FieldType.BOOLEAN_DECISION) ||
-				fieldType.equals(FieldType.RADIO_BOX) || fieldType.equals(FieldType.CURRENCY);
+				fieldType.equals(FieldType.RADIO_BOX) || fieldType.equals(FieldType.CURRENCY) || fieldType.equals(FieldType.SELECT) ||
+				fieldType.equals(FieldType.INTERNAL_DMP_ENTRIES_DMPS) || fieldType.equals(FieldType.INTERNAL_DMP_ENTRIES_DATASETS);
 	}
 
 	public static boolean isTextListType(FieldType fieldType){
diff --git a/dmp-frontend/src/app/ui/description/editor/description-editor.model.ts b/dmp-frontend/src/app/ui/description/editor/description-editor.model.ts
index 94a95087b..678244664 100644
--- a/dmp-frontend/src/app/ui/description/editor/description-editor.model.ts
+++ b/dmp-frontend/src/app/ui/description/editor/description-editor.model.ts
@@ -91,7 +91,7 @@ export class DescriptionEditorModel extends BaseEditorModel implements Descripti
 		const { formGroup, validationErrorModel } = params;
 		const control = formGroup?.get('properties');
 		DescriptionPropertyDefinitionEditorModel.reapplyValidators({
-			formArray: control.get('fieldSets') as UntypedFormArray,
+			formGroup: control.get('fieldSets') as UntypedFormGroup,
 			rootPath: `properties.`,
 			validationErrorModel: validationErrorModel
 		});
@@ -151,12 +151,22 @@ export class DescriptionPropertyDefinitionEditorModel implements DescriptionProp
 	}
 
 	static reapplyValidators(params: {
-		formArray: UntypedFormArray,
+		formGroup: UntypedFormGroup,
 		validationErrorModel: ValidationErrorModel,
 		rootPath: string
 	}): void {
 		
-		//TODO
+		const { formGroup, rootPath, validationErrorModel } = params;
+
+		const keys = Object.keys(formGroup.value as Object);
+		keys.forEach((key) => {
+			const formArray = formGroup?.get(key);
+			DescriptionPropertyDefinitionFieldSetEditorModel.reapplyValidators({
+				formArray: formArray.get('items') as UntypedFormArray,
+				rootPath: `${rootPath}fieldSets[${key}].`,
+				validationErrorModel: validationErrorModel
+			})
+		});		
 	}
 
 	private calculateProperties(item: DescriptionPropertyDefinition, descriptionTemplate: DescriptionTemplate, descriptionReferences: DescriptionReference[]): Map<string, DescriptionPropertyDefinitionFieldSetEditorModel> {
@@ -373,13 +383,22 @@ export class DescriptionPropertyDefinitionFieldSetItemEditorModel implements Des
 			validationErrorModel
 		});
 
-		//TODO
+		const fields = formGroup?.get('fields') as UntypedFormGroup;
+		const keys = Object.keys(fields.value as Object);
+		keys.forEach((key) => {
+			const control = fields?.get(key);
+			DescriptionFieldEditorModel.reapplyValidators({
+				formGroup: control as UntypedFormGroup,
+				rootPath: `${rootPath}fields.`,
+				validationErrorModel: validationErrorModel
+			})
+		});		
 
 		['comment', 'ordinal'].forEach(keyField => {
 			const control = formGroup?.get(keyField);
 			control?.clearValidators();
 			control?.addValidators(context.getValidation(keyField).validators);
-		})
+		});
 	}
 
 }
@@ -390,7 +409,7 @@ export class DescriptionFieldEditorModel implements DescriptionFieldPersist {
 	dateValue: Date;
 	references: ReferencePersist[];
 	reference: ReferencePersist;
-	externalIdentifier?: DescriptionExternalIdentifierEditorModel;
+	externalIdentifier?: DescriptionExternalIdentifierEditorModel = new DescriptionExternalIdentifierEditorModel(this.validationErrorModel);
 
 	protected formBuilder: UntypedFormBuilder = new UntypedFormBuilder();
 
@@ -428,7 +447,10 @@ export class DescriptionFieldEditorModel implements DescriptionFieldPersist {
 			textListValue: [{ value: this.textListValue, disabled: disabled }, context.getValidation('textListValue').validators],
 			dateValue: [{ value: this.dateValue, disabled: disabled }, context.getValidation('dateValue').validators],
 			references: [{ value: this.references, disabled: disabled }, context.getValidation('references').validators],
-			reference: [{ value: this.reference, disabled: disabled }, context.getValidation('reference').validators]
+			reference: [{ value: this.reference, disabled: disabled }, context.getValidation('reference').validators],
+			externalIdentifier: this.externalIdentifier.buildForm({
+				rootPath: `${rootPath}externalIdentifier.`
+			}),
 		});
 	}
 
@@ -445,6 +467,7 @@ export class DescriptionFieldEditorModel implements DescriptionFieldPersist {
 		baseValidationArray.push({ key: 'dateValue', validators: [Validators.required, BackendErrorValidator(validationErrorModel, `${rootPath}dateValue`)] });
 		baseValidationArray.push({ key: 'references', validators: [Validators.required, BackendErrorValidator(validationErrorModel, `${rootPath}references`)] });
 		baseValidationArray.push({ key: 'reference', validators: [Validators.required, BackendErrorValidator(validationErrorModel, `${rootPath}references`)] });
+		baseValidationArray.push({ key: 'externalIdentifier', validators: [BackendErrorValidator(validationErrorModel, `${rootPath}externalIdentifier`)] });
 		baseContext.validation = baseValidationArray;
 		return baseContext;
 	}
@@ -456,7 +479,7 @@ export class DescriptionFieldEditorModel implements DescriptionFieldPersist {
 	}): void {
 
 		const { formGroup, rootPath, validationErrorModel } = params;
-		const context = DescriptionPropertyDefinitionFieldSetItemEditorModel.createValidationContext({
+		const context = DescriptionFieldEditorModel.createValidationContext({
 			rootPath,
 			validationErrorModel
 		});
diff --git a/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field-set/form-field-set.component.ts b/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field-set/form-field-set.component.ts
index 6feef20bb..d3ed1c9fc 100644
--- a/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field-set/form-field-set.component.ts
+++ b/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field-set/form-field-set.component.ts
@@ -75,8 +75,8 @@ export class DescriptionFormFieldSetComponent extends BaseComponent {
 		}
 
 		const item: DescriptionPropertyDefinitionFieldSetEditorModel = new DescriptionPropertyDefinitionEditorModel(this.validationErrorModel).calculateFieldSetProperties(this.fieldSet, null, null);
-		//TODO: akis
-		formArray.push((item.buildForm({rootPath: ''}).get('items') as UntypedFormArray).at(0));
+		formArray.push((item.buildForm({rootPath: `properties.fieldSets[${this.fieldSet.id}].`}).get('items') as UntypedFormArray).at(0));
+
 	}
 
 	deleteMultiplicityField(fieldSetIndex: number): void {
@@ -86,14 +86,12 @@ export class DescriptionFormFieldSetComponent extends BaseComponent {
 			fieldSet.get('ordinal').setValue(index + 1);
 		});
 
-		//TODO: akis
 		//Reapply validators
 		DescriptionPropertyDefinitionFieldSetEditorModel.reapplyValidators(
 			{
-				formArray: this.propertiesFormGroup.get('items') as UntypedFormArray,
+				formArray: formArray,
 				validationErrorModel: this.validationErrorModel,
-				//TODO 
-				rootPath: ''
+				rootPath: `properties.fieldSets[${this.fieldSet.id}].`
 			}
 		);
 		formArray.markAsDirty();
diff --git a/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field/form-field.component.html b/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field/form-field.component.html
index c29c404f9..117e7eee6 100644
--- a/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field/form-field.component.html
+++ b/dmp-frontend/src/app/ui/description/editor/description-form/components/form-field/form-field.component.html
@@ -319,8 +319,8 @@
 		<div class="row align-items-baseline">
 			<mat-form-field class="col-md-4">
 				<input matInput class="col-md-12" [formControl]="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier')" placeholder="{{(field.data.label) + (isRequired? ' *': '')}}" [required]="isRequired">
-				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}
-				</mat-error>
+				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').hasError('backendError')">{{propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').getError('backendError').message}}</mat-error>
+				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}</mat-error>
 			</mat-form-field>
 			<mat-form-field class="col-md-4">
 				<mat-select class="col-md-12" [formControl]="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('type')" [placeholder]="('TYPES.DATASET-PROFILE-VALIDATOR.REPOSITORIES-PLACEHOLDER' | translate) + (isRequired? ' *': '')">
@@ -328,13 +328,13 @@
 						{{ type.name }}
 					</mat-option>
 				</mat-select>
-				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('type').hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}
-				</mat-error>
+				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('type').hasError('backendError')">{{propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('type').getError('backendError').message}}</mat-error>
+				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('type').hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}</mat-error>
 			</mat-form-field>
 			<div class="col-md-2">
 				<button type="button" mat-button class="lightblue-btn" (click)="validateId()" [disabled]="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').disabled">{{ "TYPES.DATASET-PROFILE-VALIDATOR.ACTION" | translate }}</button>
-				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}
-				</mat-error>
+				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').hasError('backendError')">{{propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').getError('backendError').message}}</mat-error>
+				<mat-error *ngIf="propertiesFormGroup?.get(field.id).get('externalIdentifier')?.get('identifier').hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}</mat-error>
 			</div>
 			<div class="col-md-1">
 				<mat-progress-spinner *ngIf="validationIcon === 'loading'" mode="indeterminate" [diameter]="24"></mat-progress-spinner>