diff --git a/editor/editor_file_system.cpp b/editor/editor_file_system.cpp
index 286db917a83..53ee85fbbdb 100644
--- a/editor/editor_file_system.cpp
+++ b/editor/editor_file_system.cpp
@@ -322,13 +322,14 @@ void EditorFileSystem::_save_filesystem_cache() {
 
 	FileAccess *f = FileAccess::open(fscache, FileAccess::WRITE);
 	if (f == NULL) {
-		ERR_PRINTS("Error writing fscache: " + fscache);
-	} else {
-		f->store_line(filesystem_settings_version_for_import);
-		_save_filesystem_cache(filesystem, f);
-		f->close();
-		memdelete(f);
+		ERR_EXPLAIN("Cannot create file '" + fscache + "'. Check user write permissions.");
+		ERR_FAIL();
 	}
+
+	f->store_line(filesystem_settings_version_for_import);
+	_save_filesystem_cache(filesystem, f);
+	f->close();
+	memdelete(f);
 }
 
 void EditorFileSystem::_thread_func(void *_userdata) {
@@ -1370,6 +1371,10 @@ void EditorFileSystem::_save_late_updated_files() {
 	//files that already existed, and were modified, need re-scanning for dependencies upon project restart. This is done via saving this special file
 	String fscache = EditorSettings::get_singleton()->get_project_settings_dir().plus_file("filesystem_update4");
 	FileAccessRef f = FileAccess::open(fscache, FileAccess::WRITE);
+	if (!f) {
+		ERR_EXPLAIN("Cannot create file '" + fscache + "'. Check user write permissions.");
+		ERR_FAIL();
+	}
 	for (Set<String>::Element *E = late_update_files.front(); E; E = E->next()) {
 		f->store_line(E->get());
 	}
diff --git a/editor/editor_resource_preview.cpp b/editor/editor_resource_preview.cpp
index 173333dac9e..f56cfc12a29 100644
--- a/editor/editor_resource_preview.cpp
+++ b/editor/editor_resource_preview.cpp
@@ -177,6 +177,10 @@ void EditorResourcePreview::_generate_preview(Ref<ImageTexture> &r_texture, Ref<
 				ResourceSaver::save(cache_base + "_small.png", r_small_texture);
 			}
 			FileAccess *f = FileAccess::open(cache_base + ".txt", FileAccess::WRITE);
+			if (!f) {
+				ERR_EXPLAIN("Cannot create file '" + cache_base + ".txt'. Check user write permissions.");
+				ERR_FAIL();
+			}
 			f->store_line(itos(thumbnail_size));
 			f->store_line(itos(has_small_texture));
 			f->store_line(itos(FileAccess::get_modified_time(p_item.path)));
@@ -267,10 +271,16 @@ void EditorResourcePreview::_thread() {
 								//update modified time
 
 								f = FileAccess::open(file, FileAccess::WRITE);
-								f->store_line(itos(modtime));
-								f->store_line(itos(has_small_texture));
-								f->store_line(md5);
-								memdelete(f);
+								if (!f) {
+									// Not returning as this would leave the thread hanging and would require
+									// some proper cleanup/disabling of resource preview generation.
+									ERR_PRINTS("Cannot create file '" + file + "'. Check user write permissions.");
+								} else {
+									f->store_line(itos(modtime));
+									f->store_line(itos(has_small_texture));
+									f->store_line(md5);
+									memdelete(f);
+								}
 							}
 						} else {
 							memdelete(f);