diff --git a/src/backend/model/fileprocessing/PhotoProcessing.ts b/src/backend/model/fileprocessing/PhotoProcessing.ts
index 75fe80cd..0c26e7de 100644
--- a/src/backend/model/fileprocessing/PhotoProcessing.ts
+++ b/src/backend/model/fileprocessing/PhotoProcessing.ts
@@ -17,6 +17,7 @@ import {PersonWithSampleRegion} from '../../../common/entities/PersonDTO';
 export class PhotoProcessing {
   private static initDone = false;
   private static taskQue: ITaskExecuter<RendererInput, void> = null;
+  private static readonly CONVERTED_EXTENSION = '.webp';
 
   public static init(): void {
     if (this.initDone === true) {
@@ -122,7 +123,7 @@ export class PhotoProcessing {
     return path.join(
       ProjectPath.TranscodedFolder,
       ProjectPath.getRelativePathToImages(path.dirname(mediaPath)),
-      file + '_' + size + 'q' + Config.Server.Media.Thumbnail.quality + '.webp'
+      file + '_' + size + 'q' + Config.Server.Media.Thumbnail.quality + PhotoProcessing.CONVERTED_EXTENSION
     );
   }
 
@@ -147,7 +148,7 @@ export class PhotoProcessing {
         .digest('hex') +
       '_' +
       size +
-      '.webp'
+      PhotoProcessing.CONVERTED_EXTENSION
     );
   }
 
@@ -162,6 +163,10 @@ export class PhotoProcessing {
       )
     );
 
+    if (path.extname(convertedPath) !== PhotoProcessing.CONVERTED_EXTENSION) {
+      return false;
+    }
+
     const sizeStr = convertedPath.substring(
       convertedPath.lastIndexOf('_') + 1,
       convertedPath.lastIndexOf('q')
diff --git a/src/backend/model/jobs/jobs/FileJob.ts b/src/backend/model/jobs/jobs/FileJob.ts
index 7e380839..9a41bb49 100644
--- a/src/backend/model/jobs/jobs/FileJob.ts
+++ b/src/backend/model/jobs/jobs/FileJob.ts
@@ -149,8 +149,8 @@ export abstract class FileJob<S extends { indexedOnly: boolean } = { indexedOnly
     Logger.silly(LOG_TAG, 'Loading files from db');
 
     const connection = await SQLConnection.getConnection();
-    if (this.scanFilter.noVideo === false ||
-      this.scanFilter.noPhoto === false) {
+    if (!this.scanFilter.noVideo ||
+      !this.scanFilter.noPhoto) {
 
       let usedEntity = MediaEntity;
 
@@ -179,7 +179,7 @@ export abstract class FileJob<S extends { indexedOnly: boolean } = { indexedOnly
         );
       }
     }
-    if (this.scanFilter.noMetaFile === false) {
+    if (!this.scanFilter.noMetaFile) {
 
       const result = await connection
         .getRepository(FileEntity)
diff --git a/src/backend/model/jobs/jobs/ThumbnailGenerationJob.ts b/src/backend/model/jobs/jobs/ThumbnailGenerationJob.ts
index 408281a4..23cb3845 100644
--- a/src/backend/model/jobs/jobs/ThumbnailGenerationJob.ts
+++ b/src/backend/model/jobs/jobs/ThumbnailGenerationJob.ts
@@ -1,11 +1,11 @@
-import { Config } from '../../../../common/config/private/Config';
-import { DefaultsJobs } from '../../../../common/entities/job/JobDTO';
-import { FileJob } from './FileJob';
-import { PhotoProcessing } from '../../fileprocessing/PhotoProcessing';
-import { ThumbnailSourceType } from '../../threading/PhotoWorker';
-import { MediaDTOUtils } from '../../../../common/entities/MediaDTO';
-import { FileDTO } from '../../../../common/entities/FileDTO';
-import { backendTexts } from '../../../../common/BackendTexts';
+import {Config} from '../../../../common/config/private/Config';
+import {DefaultsJobs} from '../../../../common/entities/job/JobDTO';
+import {FileJob} from './FileJob';
+import {PhotoProcessing} from '../../fileprocessing/PhotoProcessing';
+import {ThumbnailSourceType} from '../../threading/PhotoWorker';
+import {MediaDTOUtils} from '../../../../common/entities/MediaDTO';
+import {FileDTO} from '../../../../common/entities/FileDTO';
+import {backendTexts} from '../../../../common/BackendTexts';
 
 export class ThumbnailGenerationJob extends FileJob<{
   sizes: number[];
@@ -14,7 +14,7 @@ export class ThumbnailGenerationJob extends FileJob<{
   public readonly Name = DefaultsJobs[DefaultsJobs['Thumbnail Generation']];
 
   constructor() {
-    super({ noMetaFile: true });
+    super({noMetaFile: true});
     this.ConfigTemplate.push({
       id: 'sizes',
       type: 'number-array',
@@ -33,12 +33,19 @@ export class ThumbnailGenerationJob extends FileJob<{
     soloRun = false,
     allowParallelRun = false
   ): Promise<void> {
+    if (!config.sizes || !Array.isArray(config.sizes) || config.sizes.length === 0) {
+      throw new Error(
+        'unknown thumbnails sizes: ' +
+        config.sizes +
+        '. It should be an array from:' + Config.Client.Media.Thumbnail.thumbnailSizes
+      );
+    }
     for (const item of config.sizes) {
       if (Config.Client.Media.Thumbnail.thumbnailSizes.indexOf(item) === -1) {
         throw new Error(
           'unknown thumbnails size: ' +
-            item +
-            '. Add it to the possible thumbnail sizes.'
+          item +
+          '. Add it to the possible thumbnail sizes.'
         );
       }
     }
@@ -60,6 +67,7 @@ export class ThumbnailGenerationJob extends FileJob<{
         return true;
       }
     }
+    return false;
   }
 
   protected async processFile(mPath: string): Promise<void> {