diff --git a/client/js/api.js b/client/js/api.js
index 5bde6d81..d3f74c26 100644
--- a/client/js/api.js
+++ b/client/js/api.js
@@ -294,11 +294,16 @@ class Api extends events.EventTarget {
         // transform the request: upload each file, then make the request use
         // its tokens.
         data = Object.assign({}, data);
+        let fileData = {};
         let abortFunction = () => {};
         let promise = Promise.resolve();
         if (files) {
             for (let key of Object.keys(files)) {
                 const file = files[key];
+                if (file === null) {
+                    fileData[key] = null;
+                    continue;
+                }
                 const fileId = this._getFileId(file);
                 if (fileTokens[fileId]) {
                     data[key + "Token"] = fileTokens[fileId];
@@ -324,7 +329,7 @@ class Api extends events.EventTarget {
                     url,
                     requestFactory,
                     data,
-                    {},
+                    fileData,
                     options
                 );
                 abortFunction = () => requestPromise.abort();
@@ -388,7 +393,7 @@ class Api extends events.EventTarget {
             if (files) {
                 for (let key of Object.keys(files)) {
                     const value = files[key];
-                    if (value.constructor === String) {
+                    if (value !== null && value.constructor === String) {
                         data[key + "Url"] = value;
                     } else {
                         req.attach(key, value || new Blob());
diff --git a/client/js/controllers/post_main_controller.js b/client/js/controllers/post_main_controller.js
index 95cfdb52..0634069a 100644
--- a/client/js/controllers/post_main_controller.js
+++ b/client/js/controllers/post_main_controller.js
@@ -178,15 +178,11 @@ class PostMainController extends BasePostController {
         if (e.detail.relations !== undefined) {
             post.relations = e.detail.relations;
         }
-        if (e.detail.content !== undefined) {
-            post.newContent = e.detail.content;
-        }
-        if (e.detail.thumbnail !== undefined) {
-            post.newThumbnail = e.detail.thumbnail;
-        }
         if (e.detail.source !== undefined) {
             post.source = e.detail.source;
         }
+        post.newContent = e.detail.content;
+        post.newThumbnail = e.detail.thumbnail;
         post.save().then(
             () => {
                 this._view.sidebarControl.showSuccess("Post saved.");
diff --git a/client/js/controls/post_edit_sidebar_control.js b/client/js/controls/post_edit_sidebar_control.js
index 3f31f76f..9f2d37da 100644
--- a/client/js/controls/post_edit_sidebar_control.js
+++ b/client/js/controls/post_edit_sidebar_control.js
@@ -138,10 +138,7 @@ class PostEditSidebarControl extends events.EventTarget {
             this._thumbnailRemovalLinkNode.addEventListener("click", (e) =>
                 this._evtRemoveThumbnailClick(e)
             );
-            this._thumbnailRemovalLinkNode.style.display = this._post
-                .customThumbnailUrl
-                ? "block"
-                : "none";
+            this._thumbnailRemovalLinkUpdate(this._post);
         }
 
         if (this._addNoteLinkNode) {
@@ -249,12 +246,25 @@ class PostEditSidebarControl extends events.EventTarget {
         this._poolsExpander.title = `Pools (${this._post.pools.length})`;
     }
 
+    _thumbnailRemovalLinkUpdate(post) {
+        if (this._thumbnailRemovalLinkNode) {
+            this._thumbnailRemovalLinkNode.style.display = post
+                .customThumbnailUrl
+                ? "block"
+                : "none";
+        }
+    }
+
     _evtPostContentChange(e) {
         this._contentFileDropper.reset();
+        this._thumbnailRemovalLinkUpdate(e.detail.post);
+        this._newPostContent = null;
     }
 
     _evtPostThumbnailChange(e) {
         this._thumbnailFileDropper.reset();
+        this._thumbnailRemovalLinkUpdate(e.detail.post);
+        this._newPostThumbnail = undefined;
     }
 
     _evtRemoveThumbnailClick(e) {
@@ -427,9 +437,7 @@ class PostEditSidebarControl extends events.EventTarget {
                         : undefined,
 
                     thumbnail:
-                        this._newPostThumbnail !== undefined
-                            ? this._newPostThumbnail
-                            : undefined,
+                        this._newPostThumbnail,
 
                     source: this._sourceInputNode
                         ? this._sourceInputNode.value