diff --git a/src/datasources/db/cargobikeAPI.ts b/src/datasources/db/cargobikeAPI.ts
index ff47082..40f7093 100644
--- a/src/datasources/db/cargobikeAPI.ts
+++ b/src/datasources/db/cargobikeAPI.ts
@@ -20,7 +20,6 @@ This file is part of fLotte-API-Server.
 import { DataSource } from 'apollo-datasource';
 import { Connection, EntityManager, getConnection } from 'typeorm';
 import { CargoBike } from '../../model/CargoBike';
-import { GraphQLError } from 'graphql';
 import { BikeEvent } from '../../model/BikeEvent';
 import { Equipment } from '../../model/Equipment';
 import { Engagement } from '../../model/Engagement';
@@ -29,8 +28,9 @@ import { TimeFrame } from '../../model/TimeFrame';
 import { ActionLogger, DBUtils, genBoxDimensions, LockUtils } from './utils';
 import { EquipmentType } from '../../model/EquipmentType';
 import { BikeEventType } from '../../model/BikeEventType';
-import { UserInputError } from 'apollo-server-express';
 import { Actions } from '../../model/ActionLog';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
+import { NotFoundError } from '../../errors/NotFoundError';
 
 /**
  * extended datasource to feed resolvers with data about cargoBikes
@@ -83,10 +83,16 @@ export class CargoBikeAPI extends DataSource {
     }
 
     async lockCargoBike (id: number, userId: number) {
+        if (!await this.connection.getRepository(CargoBike).findOne(id)) {
+            throw new NotFoundError('CargoBike', 'id', id);
+        }
         return await LockUtils.lockEntity(this.connection, CargoBike, 'cb', id, userId);
     }
 
     async unlockCargoBike (id: number, userId: number) {
+        if (!await this.connection.getRepository(CargoBike).findOne(id)) {
+            throw new NotFoundError('CargoBike', 'id', id);
+        }
         return await LockUtils.unlockEntity(this.connection, CargoBike, 'cb', id, userId);
     }
 
@@ -107,7 +113,7 @@ export class CargoBikeAPI extends DataSource {
 
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, CargoBike, 'cb', cargoBike.id, userId)) {
-                throw new GraphQLError('CargoBike locked by other user');
+                throw new ResourceLockedError('CargoBike');
             }
             await ActionLogger.log(entityManager, CargoBike, 'cb', cargoBike, userId);
             await entityManager.getRepository(CargoBike)
@@ -116,11 +122,13 @@ export class CargoBikeAPI extends DataSource {
                 .set({ ...cargoBike })
                 .where('id = :id', { id: cargoBike.id })
                 .execute();
+
             equipmentTypeIds && await entityManager.getRepository(CargoBike)
                 .createQueryBuilder('cb')
                 .relation(CargoBike, 'equipmentTypeIds')
                 .of(cargoBike.id)
                 .addAndRemove(equipmentTypeIds, await this.equipmentTypeByCargoBikeId(cargoBike.id));
+
             equipmentIds && await entityManager.getRepository(CargoBike)
                 .createQueryBuilder('cb')
                 .relation(CargoBike, 'equipmentIds')
@@ -134,7 +142,7 @@ export class CargoBikeAPI extends DataSource {
     async deleteCargoBike (id: number, userId: number) {
         return await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, CargoBike, 'cb', id, userId)) {
-                throw new UserInputError('Attempting to soft delete locked resource');
+                throw new ResourceLockedError('CargoBike', 'Attempting to soft delete locked resource');
             }
             await ActionLogger.log(entityManager, CargoBike, 'bg', { id: id }, userId, Actions.SOFT_DELETE);
             return await entityManager.getRepository(CargoBike)
@@ -189,7 +197,7 @@ export class CargoBikeAPI extends DataSource {
         delete bikeEvent.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, BikeEvent, 'be', bikeEvent.id, userId)) {
-                throw new GraphQLError('BikeEvent locked by other user');
+                throw new ResourceLockedError('BikeEvents');
             }
             await ActionLogger.log(entityManager, BikeEvent, 'be', bikeEvent, userId);
             await entityManager.getRepository(BikeEvent)
@@ -267,7 +275,7 @@ export class CargoBikeAPI extends DataSource {
         delete bikeEventType.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, BikeEventType, 'bet', bikeEventType.id, userId)) {
-                throw new GraphQLError('BikeEventType locked by other user');
+                throw new ResourceLockedError('BikeEventType');
             }
             await ActionLogger.log(entityManager, BikeEventType, 'bet', bikeEventType, userId);
             await entityManager.getRepository(BikeEventType)
@@ -405,7 +413,7 @@ export class CargoBikeAPI extends DataSource {
         delete equipment.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, Equipment, 'equipment', equipment.id, userId)) {
-                return new GraphQLError('Equipment is locked by other user');
+                throw new ResourceLockedError('Equipment');
             }
             await ActionLogger.log(entityManager, Equipment, 'e', equipment, userId);
             await entityManager.getRepository(Equipment)
@@ -453,7 +461,7 @@ export class CargoBikeAPI extends DataSource {
         delete equipmentType.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, EquipmentType, 'et', equipmentType.id, userId)) {
-                throw new GraphQLError('EquipmentType is locked by other user');
+                throw new ResourceLockedError('EquipmentType');
             }
             await ActionLogger.log(entityManager, EquipmentType, 'et', equipmentType, userId);
             await entityManager.getRepository(EquipmentType)
diff --git a/src/datasources/db/contactinformationAPI.ts b/src/datasources/db/contactinformationAPI.ts
index e3e9a28..10e7959 100644
--- a/src/datasources/db/contactinformationAPI.ts
+++ b/src/datasources/db/contactinformationAPI.ts
@@ -22,8 +22,9 @@ import { Connection, EntityManager, getConnection } from 'typeorm';
 import { ContactInformation } from '../../model/ContactInformation';
 import { Person } from '../../model/Person';
 import { ActionLogger, DBUtils, LockUtils } from './utils';
-import { GraphQLError } from 'graphql';
 import { LendingStation } from '../../model/LendingStation';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
+import { NotFoundError } from '../../errors/NotFoundError';
 
 export class ContactInformationAPI extends DataSource {
     connection : Connection
@@ -68,7 +69,7 @@ export class ContactInformationAPI extends DataSource {
         delete person.keepLock;
         await this.connection.transaction(async (entityManger: EntityManager) => {
             if (await LockUtils.isLocked(entityManger, Person, 'p', person.id, userId)) {
-                throw new GraphQLError('Person is locker by another user');
+                throw new ResourceLockedError('Person');
             }
             await ActionLogger.log(entityManger, Person, 'p', person, userId);
             await entityManger.getRepository(Person)
@@ -76,7 +77,11 @@ export class ContactInformationAPI extends DataSource {
                 .update()
                 .set({ ...person })
                 .where('id = :id', { id: person.id })
-                .execute().then(value => { if (value.affected !== 1) { throw new GraphQLError('Id not found'); } });
+                .execute().then(value => {
+                    if (value.affected !== 1) {
+                        throw new NotFoundError('Person', 'id', person.id);
+                    }
+                });
         });
         !keepLock && await this.unlockPerson(person.id, userId);
         return this.personById(person.id);
@@ -146,7 +151,7 @@ export class ContactInformationAPI extends DataSource {
         delete contactInformation.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, ContactInformation, 'ci', contactInformation.id, userId)) {
-                throw new GraphQLError('ContactInformation is locked by other user');
+                throw new ResourceLockedError('ContactInformation');
             }
             await ActionLogger.log(entityManager, ContactInformation, 'ci', contactInformation, userId);
             await entityManager.getRepository(ContactInformation)
diff --git a/src/datasources/db/lendingstationAPI.ts b/src/datasources/db/lendingstationAPI.ts
index 52c08ad..02ab251 100644
--- a/src/datasources/db/lendingstationAPI.ts
+++ b/src/datasources/db/lendingstationAPI.ts
@@ -24,6 +24,7 @@ import { CargoBike } from '../../model/CargoBike';
 import { LendingStation } from '../../model/LendingStation';
 import { TimeFrame } from '../../model/TimeFrame';
 import { ActionLogger, genDateRange, DBUtils, LockUtils } from './utils';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
 
 export class LendingStationAPI extends DataSource {
     connection : Connection
@@ -163,7 +164,7 @@ export class LendingStationAPI extends DataSource {
         delete lendingStation.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, LendingStation, 'ls', lendingStation.id, userId)) {
-                throw new UserInputError('Attempting to update locked resource');
+                throw new ResourceLockedError('LendingStation', 'Attempting to update locked resource');
             }
             await ActionLogger.log(entityManager, LendingStation, 'ls', lendingStation, userId);
             await entityManager.getRepository(LendingStation)
@@ -222,7 +223,7 @@ export class LendingStationAPI extends DataSource {
         delete timeFrame.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, TimeFrame, 'tf', timeFrame.id, userId)) {
-                throw new UserInputError('Attempting to update locked resource');
+                throw new ResourceLockedError('TimeFrame', 'Attempting to update locked resource');
             }
             genDateRange(timeFrame);
             await ActionLogger.log(entityManager, TimeFrame, 'tf', timeFrame, userId);
diff --git a/src/datasources/db/participantAPI.ts b/src/datasources/db/participantAPI.ts
index 270ec09..8efd5b8 100644
--- a/src/datasources/db/participantAPI.ts
+++ b/src/datasources/db/participantAPI.ts
@@ -26,6 +26,7 @@ import { EngagementType } from '../../model/EngagementType';
 import { ActionLogger, DBUtils, genDateRange, LockUtils } from './utils';
 import { UserInputError } from 'apollo-server-express';
 import { GraphQLError } from 'graphql';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
 
 export class ParticipantAPI extends DataSource {
     connection : Connection
@@ -202,7 +203,7 @@ export class ParticipantAPI extends DataSource {
         delete participant.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, Participant, 'p', participant.id, userId)) {
-                throw new UserInputError('Attempting to update locked resource');
+                throw new ResourceLockedError('Participant', 'Attempting to update locked resource');
             }
             genDateRange(participant);
             const workshops = participant.workshopIds;
@@ -288,7 +289,7 @@ export class ParticipantAPI extends DataSource {
         genDateRange(engagement);
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, Engagement, 'e', engagement.id, userId)) {
-                throw new GraphQLError('Engagement is locked by other user');
+                throw new ResourceLockedError('Engagement');
             }
             await ActionLogger.log(entityManager, Engagement, 'e', engagement, userId);
             // check for overlapping engagements
@@ -356,7 +357,7 @@ export class ParticipantAPI extends DataSource {
         delete engagementType.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, EngagementType, 'et', engagementType.id, userId)) {
-                throw new GraphQLError('EngagementType is locked by other user');
+                throw new ResourceLockedError('EngagementType');
             }
             await ActionLogger.log(entityManager, EngagementType, 'et', engagementType, userId);
             await entityManager.getRepository(EngagementType)
diff --git a/src/datasources/db/providerAPI.ts b/src/datasources/db/providerAPI.ts
index 56df367..30fabc3 100644
--- a/src/datasources/db/providerAPI.ts
+++ b/src/datasources/db/providerAPI.ts
@@ -25,7 +25,8 @@ import { UserInputError } from 'apollo-server-express';
 import { CargoBike } from '../../model/CargoBike';
 import { LendingStation } from '../../model/LendingStation';
 import { ActionLogger, DBUtils, LockUtils } from './utils';
-import { GraphQLError } from 'graphql';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
+import { NotFoundError } from '../../errors/NotFoundError';
 
 export class ProviderAPI extends DataSource {
     connection : Connection
@@ -150,7 +151,7 @@ export class ProviderAPI extends DataSource {
         delete provider.cargoBikeIds;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, Provider, 'p', provider.id, userId)) {
-                throw new GraphQLError('Provider is locked by another user');
+                throw new ResourceLockedError('Provider');
             }
             await ActionLogger.log(entityManager, Provider, 'p', provider, userId);
             await entityManager.getRepository(Provider)
@@ -158,7 +159,11 @@ export class ProviderAPI extends DataSource {
                 .update()
                 .set({ ...provider })
                 .where('id = :id', { id: provider.id })
-                .execute().then(value => { if (value.affected !== 1) { throw new GraphQLError('ID not found'); } });
+                .execute().then(value => {
+                    if (value.affected !== 1) {
+                        throw new NotFoundError('Provider', 'id', provider.id);
+                    }
+                });
             await entityManager.getRepository(Provider)
                 .createQueryBuilder('p')
                 .relation(Provider, 'cargoBikeIds')
@@ -198,7 +203,7 @@ export class ProviderAPI extends DataSource {
         delete organisation.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, Organisation, 'o', organisation.id, userId)) {
-                throw new GraphQLError('Organisation is locked by another user');
+                throw new ResourceLockedError('Organisation');
             }
             await ActionLogger.log(entityManager, Organisation, 'o', organisation, userId);
             await entityManager.getRepository(Organisation)
diff --git a/src/datasources/db/utils.ts b/src/datasources/db/utils.ts
index 7262417..d377977 100644
--- a/src/datasources/db/utils.ts
+++ b/src/datasources/db/utils.ts
@@ -21,6 +21,8 @@ import { Connection, EntityManager, ObjectType } from 'typeorm';
 import { Lockable } from '../../model/CargoBike';
 import { ActionLog, Actions } from '../../model/ActionLog';
 import { UserInputError } from 'apollo-server-express';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
+import { NotFoundError } from '../../errors/NotFoundError';
 
 export function genDateRange (struct: any) {
     if (!struct.dateRange || !struct.dateRange.from) {
@@ -100,7 +102,7 @@ export class DBUtils {
     static async deleteEntity (connection: Connection, target: ObjectType<Lockable>, alias: string, id: number, userId: number): Promise<Boolean> {
         return await connection.transaction(async (entityManger: EntityManager) => {
             if (await LockUtils.isLocked(entityManger, target, alias, id, userId)) {
-                throw new UserInputError('Attempting to delete locked resource');
+                throw new ResourceLockedError('Connection', 'Attempting to delete locked resource');
             }
             await ActionLogger.log(entityManger, target, alias, { id: id }, userId, Actions.DELETE);
             return await entityManger.getRepository(target)
@@ -158,7 +160,7 @@ export class LockUtils {
             .select()
             .where(alias + '.id = :id', { id: id })
             .getOne().catch(() => {
-                throw new UserInputError('ID not found');
+                throw new NotFoundError(target.name, 'id', id);
             });
     }
 
@@ -301,7 +303,7 @@ export class ActionLogger {
             .where('id = :id', { id: updates.id })
             .getRawOne().then(value => {
                 if (value === undefined) {
-                    throw new UserInputError('Id not found');
+                    throw new NotFoundError(target.name, 'id', updates.id);
                 }
                 return value;
             }); // use getRawOne to also get ids of related entities
diff --git a/src/datasources/db/workshopAPI.ts b/src/datasources/db/workshopAPI.ts
index c6ba9d8..9c0e510 100644
--- a/src/datasources/db/workshopAPI.ts
+++ b/src/datasources/db/workshopAPI.ts
@@ -22,9 +22,9 @@ import { Connection, EntityManager, getConnection } from 'typeorm';
 import { WorkshopType } from '../../model/WorkshopType';
 import { Workshop } from '../../model/Workshop';
 import { ActionLogger, DBUtils, LockUtils } from './utils';
-import { UserInputError } from 'apollo-server-express';
-import { GraphQLError } from 'graphql';
 import { Participant } from '../../model/Participant';
+import { ResourceLockedError } from '../../errors/ResourceLockedError';
+import { NotFoundError } from '../../errors/NotFoundError';
 
 export class WorkshopAPI extends DataSource {
     connection: Connection
@@ -57,7 +57,7 @@ export class WorkshopAPI extends DataSource {
         delete workshop.keepLock;
         await this.connection.transaction(async (entityManger: EntityManager) => {
             if (await LockUtils.isLocked(entityManger, Workshop, 'w', workshop.id, userId)) {
-                throw new UserInputError('Attempting to update locked resource');
+                throw new ResourceLockedError('Workshop', 'Attempting to update locked resource');
             }
             await ActionLogger.log(entityManger, Workshop, 'w', workshop, userId);
             await entityManger.getRepository(Workshop)
@@ -66,7 +66,11 @@ export class WorkshopAPI extends DataSource {
                 .set({ ...workshop })
                 .where('id = :id', { id: workshop.id })
                 .execute()
-                .then(value => { if (value.affected !== 1) { throw new GraphQLError('ID not found'); } });
+                .then(value => {
+                    if (value.affected !== 1) {
+                        throw new NotFoundError('Workshop', 'id', workshop.id);
+                    }
+                });
         });
         !keepLock && await this.unlockWorkshop(workshop.id, userId);
         return await this.workshopById(workshop.id);
@@ -99,7 +103,7 @@ export class WorkshopAPI extends DataSource {
         delete workshopType.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, WorkshopType, 'wt', workshopType.id, userId)) {
-                throw new UserInputError('Attempting to update locked resource');
+                throw new ResourceLockedError('WorkshopType', 'Attempting to update locked resource');
             }
             await ActionLogger.log(entityManager, WorkshopType, 'wt', workshopType, userId);
             await entityManager.getRepository(WorkshopType)
@@ -108,7 +112,11 @@ export class WorkshopAPI extends DataSource {
                 .set({ ...workshopType })
                 .where('id = :id', { id: workshopType.id })
                 .execute()
-                .then(value => { if (value.affected !== 1) { throw new GraphQLError('ID not found'); } });
+                .then(value => {
+                    if (value.affected !== 1) {
+                        throw new NotFoundError('WorkshopType', 'id', workshopType.id);
+                    }
+                });
         });
         !keepLock && await this.unlockWorkshopType(workshopType.id, userId);
         return await this.workshopTypeById(workshopType.id);
diff --git a/src/errors/NotFoundError.ts b/src/errors/NotFoundError.ts
new file mode 100644
index 0000000..d0d1ecf
--- /dev/null
+++ b/src/errors/NotFoundError.ts
@@ -0,0 +1,7 @@
+import { ApolloError } from 'apollo-server-express';
+
+export class NotFoundError extends ApolloError {
+    constructor (type: string, identifierParam: string, identifierValue: any) {
+        super(`${type} with ${identifierParam} = '${identifierValue}' not found.`, 'ENTITY_NOT_FOUND');
+    }
+}
diff --git a/src/errors/ResourceLockedError.ts b/src/errors/ResourceLockedError.ts
new file mode 100644
index 0000000..1b45eed
--- /dev/null
+++ b/src/errors/ResourceLockedError.ts
@@ -0,0 +1,11 @@
+import { ApolloError } from 'apollo-server-express';
+
+export class ResourceLockedError extends ApolloError {
+    constructor (resourceName: String, additionalContext?: string) {
+        if (additionalContext) {
+            super(`The Resource ${resourceName} is currently locked: ${additionalContext}`, 'LOCKED_ERROR');
+        } else {
+            super(`The Resource ${resourceName} is currently locked`, 'LOCKED_ERROR');
+        }
+    }
+}
diff --git a/tests/testQueries.ts b/tests/testQueries.ts
index 623fc75..5615cc5 100644
--- a/tests/testQueries.ts
+++ b/tests/testQueries.ts
@@ -20,9 +20,15 @@ export const CREATE_CARGO_BIKE = gql`
                 dimensionsAndLoad: {
                     hasCoverBox: true
                     lockable:false
-                    boxLength: 0.1
-                    boxWidth: 0.2
-                    boxHeight:0.3
+                    boxLengthRange: {
+                        min: 0,
+                    }
+                    boxWidthRange: {
+                        min: 0.2
+                    }
+                    boxHeightRange: {
+                        min: 0.3
+                    }
                     maxWeightBox: 1.1
                     maxWeightLuggageRack: 1.2
                     maxWeightTotal: 1.3