diff --git a/frontend/src/components/files/ListingItem.vue b/frontend/src/components/files/ListingItem.vue
index 8f4bb8ba..5e945be7 100644
--- a/frontend/src/components/files/ListingItem.vue
+++ b/frontend/src/components/files/ListingItem.vue
@@ -78,7 +78,11 @@ export default {
     },
     thumbnailUrl () {
       const path = this.url.replace(/^\/files\//, '')
-      return `${baseURL}/api/preview/thumb/${path}?auth=${this.jwt}&inline=true`
+
+      // reload the image when the file is replaced
+      const key = Date.parse(this.modified)
+
+      return `${baseURL}/api/preview/thumb/${path}?auth=${this.jwt}&inline=true&k=${key}`
     },
     isThumbsEnabled () {
       return enableThumbs
diff --git a/frontend/src/views/files/Preview.vue b/frontend/src/views/files/Preview.vue
index 21cb8ccd..495f1244 100644
--- a/frontend/src/views/files/Preview.vue
+++ b/frontend/src/views/files/Preview.vue
@@ -102,10 +102,13 @@ export default {
       return `${baseURL}/api/raw${url.encodePath(this.req.path)}?auth=${this.jwt}`
     },
     previewUrl () {
+      // reload the image when the file is replaced
+      const key = Date.parse(this.req.modified)
+
       if (this.req.type === 'image' && !this.fullSize) {
-        return `${baseURL}/api/preview/big${url.encodePath(this.req.path)}?auth=${this.jwt}`
+        return `${baseURL}/api/preview/big${url.encodePath(this.req.path)}?auth=${this.jwt}&k=${key}`
       }
-      return `${baseURL}/api/raw${url.encodePath(this.req.path)}?auth=${this.jwt}`
+      return `${baseURL}/api/raw${url.encodePath(this.req.path)}?auth=${this.jwt}&k=${key}`
     },
     raw () {
       return `${this.previewUrl}&inline=true`
diff --git a/http/http.go b/http/http.go
index 47073653..80c7e92c 100644
--- a/http/http.go
+++ b/http/http.go
@@ -54,7 +54,7 @@ func NewHandler(
 
 	api.PathPrefix("/resources").Handler(monkey(resourceGetHandler, "/api/resources")).Methods("GET")
 	api.PathPrefix("/resources").Handler(monkey(resourceDeleteHandler(fileCache), "/api/resources")).Methods("DELETE")
-	api.PathPrefix("/resources").Handler(monkey(resourcePostHandler, "/api/resources")).Methods("POST")
+	api.PathPrefix("/resources").Handler(monkey(resourcePostHandler(fileCache), "/api/resources")).Methods("POST")
 	api.PathPrefix("/resources").Handler(monkey(resourcePutHandler, "/api/resources")).Methods("PUT")
 	api.PathPrefix("/resources").Handler(monkey(resourcePatchHandler, "/api/resources")).Methods("PATCH")
 
diff --git a/http/preview.go b/http/preview.go
index 0d956a51..562562ff 100644
--- a/http/preview.go
+++ b/http/preview.go
@@ -79,7 +79,7 @@ func handleImagePreview(w http.ResponseWriter, r *http.Request, imgSvc ImgServic
 		return errToStatus(err), err
 	}
 
-	cacheKey := previewCacheKey(file.Path, previewSize)
+	cacheKey := previewCacheKey(file.Path, file.ModTime.Unix(), previewSize)
 	cachedFile, ok, err := fileCache.Load(r.Context(), cacheKey)
 	if err != nil {
 		return errToStatus(err), err
@@ -133,6 +133,6 @@ func handleImagePreview(w http.ResponseWriter, r *http.Request, imgSvc ImgServic
 	return 0, nil
 }
 
-func previewCacheKey(fPath string, previewSize PreviewSize) string {
-	return fPath + previewSize.String()
+func previewCacheKey(fPath string, fTime int64, previewSize PreviewSize) string {
+	return fmt.Sprintf("%x%x%x", fPath, fTime, previewSize)
 }
diff --git a/http/resource.go b/http/resource.go
index 16be5d89..84a5abf8 100644
--- a/http/resource.go
+++ b/http/resource.go
@@ -1,6 +1,7 @@
 package http
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -71,11 +72,9 @@ func resourceDeleteHandler(fileCache FileCache) handleFunc {
 		}
 
 		// delete thumbnails
-		for _, previewSizeName := range PreviewSizeNames() {
-			size, _ := ParsePreviewSize(previewSizeName)
-			if err := fileCache.Delete(r.Context(), previewCacheKey(file.Path, size)); err != nil { //nolint:govet
-				return errToStatus(err), err
-			}
+		err = delThumbs(r.Context(), fileCache, file)
+		if err != nil {
+			return errToStatus(err), err
 		}
 
 		err = d.RunHook(func() error {
@@ -90,41 +89,56 @@ func resourceDeleteHandler(fileCache FileCache) handleFunc {
 	})
 }
 
-var resourcePostHandler = withUser(func(w http.ResponseWriter, r *http.Request, d *data) (int, error) {
-	if !d.user.Perm.Create {
-		return http.StatusForbidden, nil
-	}
-
-	defer func() {
-		_, _ = io.Copy(ioutil.Discard, r.Body)
-	}()
-
-	// Directories creation on POST.
-	if strings.HasSuffix(r.URL.Path, "/") {
-		err := d.user.Fs.MkdirAll(r.URL.Path, 0775)
-		return errToStatus(err), err
-	}
-
-	if r.URL.Query().Get("override") != "true" {
-		if _, err := d.user.Fs.Stat(r.URL.Path); err == nil {
-			return http.StatusConflict, nil
+func resourcePostHandler(fileCache FileCache) handleFunc {
+	return withUser(func(w http.ResponseWriter, r *http.Request, d *data) (int, error) {
+		if !d.user.Perm.Create {
+			return http.StatusForbidden, nil
 		}
-	}
 
-	err := d.RunHook(func() error {
-		info, _ := writeFile(d.user.Fs, r.URL.Path, r.Body)
+		defer func() {
+			_, _ = io.Copy(ioutil.Discard, r.Body)
+		}()
 
-		etag := fmt.Sprintf(`"%x%x"`, info.ModTime().UnixNano(), info.Size())
-		w.Header().Set("ETag", etag)
-		return nil
-	}, "upload", r.URL.Path, "", d.user)
+		// Directories creation on POST.
+		if strings.HasSuffix(r.URL.Path, "/") {
+			err := d.user.Fs.MkdirAll(r.URL.Path, 0775)
+			return errToStatus(err), err
+		}
 
-	if err != nil {
-		_ = d.user.Fs.RemoveAll(r.URL.Path)
-	}
+		file, err := files.NewFileInfo(files.FileOptions{
+			Fs:         d.user.Fs,
+			Path:       r.URL.Path,
+			Modify:     d.user.Perm.Modify,
+			Expand:     true,
+			ReadHeader: d.server.TypeDetectionByHeader,
+			Checker:    d,
+		})
+		if err == nil {
+			if r.URL.Query().Get("override") != "true" {
+				return http.StatusConflict, nil
+			}
 
-	return errToStatus(err), err
-})
+			err = delThumbs(r.Context(), fileCache, file)
+			if err != nil {
+				return errToStatus(err), err
+			}
+		}
+
+		err = d.RunHook(func() error {
+			info, _ := writeFile(d.user.Fs, r.URL.Path, r.Body)
+
+			etag := fmt.Sprintf(`"%x%x"`, info.ModTime().UnixNano(), info.Size())
+			w.Header().Set("ETag", etag)
+			return nil
+		}, "upload", r.URL.Path, "", d.user)
+
+		if err != nil {
+			_ = d.user.Fs.RemoveAll(r.URL.Path)
+		}
+
+		return errToStatus(err), err
+	})
+}
 
 var resourcePutHandler = withUser(func(w http.ResponseWriter, r *http.Request, d *data) (int, error) {
 	if !d.user.Perm.Modify {
@@ -264,3 +278,14 @@ func writeFile(fs afero.Fs, dst string, in io.Reader) (os.FileInfo, error) {
 
 	return info, nil
 }
+
+func delThumbs(ctx context.Context, fileCache FileCache, file *files.FileInfo) error {
+	for _, previewSizeName := range PreviewSizeNames() {
+		size, _ := ParsePreviewSize(previewSizeName)
+		if err := fileCache.Delete(ctx, previewCacheKey(file.Path, file.ModTime.Unix(), size)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}