diff --git a/ReactNativeClient/src/synchronizer.js b/ReactNativeClient/src/synchronizer.js
index c5ccffdf7..8d7ea5f80 100644
--- a/ReactNativeClient/src/synchronizer.js
+++ b/ReactNativeClient/src/synchronizer.js
@@ -1,4 +1,3 @@
-import { Registry } from 'src/registry.js';
 import { Log } from 'src/log.js';
 import { Setting } from 'src/models/setting.js';
 import { Change } from 'src/models/change.js';
@@ -27,130 +26,137 @@ class Synchronizer {
 		return this.api_;
 	}
 
-	processState(state) {
-		// if (this.state() == state) {
-		// 	Log.info('Sync: cannot switch to same state: ' + state);
-		// 	return;
-		// }
-
-		Log.info('Sync: processing: ' + state);
-		this.state_ = state;
-
-		if (state == 'downloadChanges') {
-			let maxRevId = null;
-			let hasMore = false;
-			this.api().get('synchronizer', { last_id: Setting.value('sync.lastRevId') }).then((syncOperations) => {
-				hasMore = syncOperations.has_more;
-				let chain = [];
-				for (let i = 0; i < syncOperations.items.length; i++) {
-					let syncOp = syncOperations.items[i];
-					if (syncOp.id > maxRevId) maxRevId = syncOp.id;
+	processState_uploadChanges() {
+		Change.all().then((changes) => {
+			let mergedChanges = Change.mergeChanges(changes);
+			let chain = [];
+			let processedChangeIds = [];
+			for (let i = 0; i < mergedChanges.length; i++) {
+				let c = mergedChanges[i];
+				chain.push(() => {
+					let p = null;
 
 					let ItemClass = null;					
-					if (syncOp.item_type == 'folder') {
+					let path = null;
+					if (c.item_type == BaseModel.ITEM_TYPE_FOLDER) {
 						ItemClass = Folder;
-					} else if (syncOp.item_type == 'note') {
+						path = 'folders';
+					} else if (c.item_type == BaseModel.ITEM_TYPE_NOTE) {
 						ItemClass = Note;
+						path = 'notes';
 					}
 
-					if (syncOp.type == 'create') {
-						chain.push(() => {
-							let item = ItemClass.fromApiResult(syncOp.item);
-							// TODO: automatically handle NULL fields by checking type and default value of field
-							if ('parent_id' in item && !item.parent_id) item.parent_id = '';
-							return ItemClass.save(item, { isNew: true, trackChanges: false });
+					if (c.type == Change.TYPE_NOOP) {
+						p = Promise.resolve();
+					} else if (c.type == Change.TYPE_CREATE) {
+						p = ItemClass.load(c.item_id).then((item) => {
+							return this.api().put(path + '/' + item.id, null, item);
 						});
-					}
-
-					if (syncOp.type == 'update') {
-						chain.push(() => {
-							return ItemClass.load(syncOp.item_id).then((item) => {
-								if (!item) return;
-								item = ItemClass.applyPatch(item, syncOp.item);
-								return ItemClass.save(item, { trackChanges: false });
-							});
+					} else if (c.type == Change.TYPE_UPDATE) {
+						p = ItemClass.load(c.item_id).then((item) => {
+							return this.api().patch(path + '/' + item.id, null, item);
 						});
+					} else if (c.type == Change.TYPE_DELETE) {
+						p = this.api().delete(path + '/' + c.item_id);
 					}
 
-					if (syncOp.type == 'delete') {
-						chain.push(() => {
-							return ItemClass.delete(syncOp.item_id, { trackChanges: false });
-						});
-					}
-				}
-				return promiseChain(chain);
-			}).then(() => {
-				Log.info('All items synced. has_more = ', hasMore);
-				if (maxRevId) {
-					Setting.setValue('sync.lastRevId', maxRevId);
-					return Setting.saveAll();
-				}
-			}).then(() => {
-				if (hasMore) {
-					this.processState('downloadChanges');
-				} else {
-					this.processState('uploadingChanges');
-				}
-			}).catch((error) => {
-				Log.warn('Sync error', error);
-			});
-		} else if (state == 'uploadingChanges') {
-			Change.all().then((changes) => {
-				let mergedChanges = Change.mergeChanges(changes);
-				let chain = [];
-				let processedChangeIds = [];
-				for (let i = 0; i < mergedChanges.length; i++) {
-					let c = mergedChanges[i];
-					chain.push(() => {
-						let p = null;
-
-						let ItemClass = null;					
-						let path = null;
-						if (c.item_type == BaseModel.ITEM_TYPE_FOLDER) {
-							ItemClass = Folder;
-							path = 'folders';
-						} else if (c.item_type == BaseModel.ITEM_TYPE_NOTE) {
-							ItemClass = Note;
-							path = 'notes';
-						}
-
-						if (c.type == Change.TYPE_NOOP) {
-							p = Promise.resolve();
-						} else if (c.type == Change.TYPE_CREATE) {
-							p = ItemClass.load(c.item_id).then((item) => {
-								return this.api().put(path + '/' + item.id, null, item);
-							});
-						} else if (c.type == Change.TYPE_UPDATE) {
-							p = ItemClass.load(c.item_id).then((item) => {
-								return this.api().patch(path + '/' + item.id, null, item);
-							});
-						} else if (c.type == Change.TYPE_DELETE) {
-							p = this.api().delete(path + '/' + c.item_id);
-						}
-
-						return p.then(() => {
+					return p.then(() => {
+						processedChangeIds = processedChangeIds.concat(c.ids);
+					}).catch((error) => {
+						Log.warn('Failed applying changes', c.ids, error.message, error.type);
+						// This is fine - trying to apply changes to an object that has been deleted
+						if (error.type == 'NotFoundException') {
 							processedChangeIds = processedChangeIds.concat(c.ids);
-						}).catch((error) => {
-							Log.warn('Failed applying changes', c.ids, error.message, error.type);
-							// This is fine - trying to apply changes to an object that has been deleted
-							if (error.type == 'NotFoundException') {
-								processedChangeIds = processedChangeIds.concat(c.ids);
-							} else {
-								throw error;
-							}
+						} else {
+							throw error;
+						}
+					});
+				});
+			}
+
+			return promiseChain(chain).catch((error) => {
+				Log.warn('Synchronization was interrupted due to an error:', error);
+			}).then(() => {
+				Log.info('IDs to delete: ', processedChangeIds);
+				Change.deleteMultiple(processedChangeIds);
+			});
+		}).then(() => {
+			this.processState('downloadChanges');
+		});
+	}
+
+	processState_downloadChanges() {
+		let maxRevId = null;
+		let hasMore = false;
+		this.api().get('synchronizer', { last_id: Setting.value('sync.lastRevId') }).then((syncOperations) => {
+			hasMore = syncOperations.has_more;
+			let chain = [];
+			for (let i = 0; i < syncOperations.items.length; i++) {
+				let syncOp = syncOperations.items[i];
+				if (syncOp.id > maxRevId) maxRevId = syncOp.id;
+
+				let ItemClass = null;					
+				if (syncOp.item_type == 'folder') {
+					ItemClass = Folder;
+				} else if (syncOp.item_type == 'note') {
+					ItemClass = Note;
+				}
+
+				if (syncOp.type == 'create') {
+					chain.push(() => {
+						let item = ItemClass.fromApiResult(syncOp.item);
+						// TODO: automatically handle NULL fields by checking type and default value of field
+						if ('parent_id' in item && !item.parent_id) item.parent_id = '';
+						return ItemClass.save(item, { isNew: true, trackChanges: false });
+					});
+				}
+
+				if (syncOp.type == 'update') {
+					chain.push(() => {
+						return ItemClass.load(syncOp.item_id).then((item) => {
+							if (!item) return;
+							item = ItemClass.applyPatch(item, syncOp.item);
+							return ItemClass.save(item, { trackChanges: false });
 						});
 					});
 				}
 
-				return promiseChain(chain).catch((error) => {
-					Log.warn('Synchronization was interrupted due to an error:', error);
-				}).then(() => {
-					Log.info('IDs to delete: ', processedChangeIds);
-					Change.deleteMultiple(processedChangeIds);
-				});
-			}).then(() => {
+				if (syncOp.type == 'delete') {
+					chain.push(() => {
+						return ItemClass.delete(syncOp.item_id, { trackChanges: false });
+					});
+				}
+			}
+			return promiseChain(chain);
+		}).then(() => {
+			Log.info('All items synced. has_more = ', hasMore);
+			if (maxRevId) {
+				Setting.setValue('sync.lastRevId', maxRevId);
+				return Setting.saveAll();
+			}
+		}).then(() => {
+			if (hasMore) {
+				this.processState('downloadChanges');
+			} else {
 				this.processState('idle');
-			});
+			}
+		}).catch((error) => {
+			Log.warn('Sync error', error);
+		});
+	}
+
+	processState(state) {
+		Log.info('Sync: processing: ' + state);
+		this.state_ = state;
+
+		if (state == 'uploadChanges') {
+			processState_uploadChanges();
+		} else if (state == 'downloadChanges') {
+			processState_downloadChanges();
+		} else if (state == 'idle') {
+			// Nothing
+		} else {
+			throw new Error('Invalid state: ' . state);
 		}
 	}
 
@@ -167,7 +173,7 @@ class Synchronizer {
 			return;
 		}
 
-		this.processState('downloadChanges');
+		this.processState('uploadChanges');
 	}
 
 }
diff --git a/run_tests.sh b/run_tests.sh
index 1a6b6bede..57ea97870 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -1,2 +1,3 @@
 #!/bin/bash
-php phpunit-5.7.20.phar --bootstrap vendor/autoload.php tests/Model/
\ No newline at end of file
+# php phpunit-5.7.20.phar --bootstrap vendor/autoload.php tests/Model/
+php phpunit-5.7.20.phar --filter testConflict ChangeTest tests/Model/ChangeTest.php --bootstrap vendor/autoload.php tests/Model/
\ No newline at end of file
diff --git a/src/AppBundle/Model/Change.php b/src/AppBundle/Model/Change.php
index 6196f8ed0..b11fdce03 100755
--- a/src/AppBundle/Model/Change.php
+++ b/src/AppBundle/Model/Change.php
@@ -47,13 +47,8 @@ class Change extends BaseModel {
 			}
 
 			$itemIdToChange[$change->item_id] = $change;
-
-			// echo BaseModel::hex($change->item_id) . ' ' . $change->id . ' ' . Change::enumName('type', $change->type) . "\n";
 		}
 
-		// die();
-
-
 		$output = array();
 		foreach ($itemIdToChange as $itemId => $change) {
 			if (in_array($itemId, $createdItems) && in_array($itemId, $deletedItems)) {
diff --git a/src/AppBundle/Model/Note.php b/src/AppBundle/Model/Note.php
index 879f2c0bd..bdcf9dc4f 100755
--- a/src/AppBundle/Model/Note.php
+++ b/src/AppBundle/Model/Note.php
@@ -30,7 +30,7 @@ class Note extends BaseItem {
 		'source_url' => null,
 	);
 
-	static public function filter($data) {
+	static public function filter($data, $keepId = false) {
 		$output = parent::filter($data);
 		if (array_key_exists('longitude', $output)) $output['longitude'] = (string)number_format($output['longitude'], 8);
 		if (array_key_exists('latitude', $output)) $output['latitude'] = (string)number_format($output['latitude'], 8);
diff --git a/tests/Model/ChangeTest.php b/tests/Model/ChangeTest.php
index 1601c0d46..13ce43763 100755
--- a/tests/Model/ChangeTest.php
+++ b/tests/Model/ChangeTest.php
@@ -48,6 +48,66 @@ class ChangeTest extends BaseTestCase {
 		$this->assertEquals($r, $text2);
 	}
 
+	public function testConflict() {
+		// Scenario where two different clients change the same note at the same time.
+		//
+		// Client 1: 'abcd efgh ijkl' => 'XXXX'
+		// Client 2: 'abcd efgh ijkl' => 'YYYY'
+		// Expected: 'cd CLIENT1 efgh ijkl FROMCLIENT2'
+
+		$text1 = 'abcd efgh ijkl';
+
+		$itemId = $this->createModelId('note');
+
+		$change = new Change();
+		$change->user_id = $this->user()->id;
+		$change->client_id = $this->clientId(1);
+		$change->item_type = BaseItem::enumId('type', 'note');
+		$change->item_field = 'body';
+		$change->type = Change::enumId('type', 'create');
+		$change->item_id = $itemId;
+		$change->createDelta($text1);
+		$change->save();
+
+		$changeId1 = $change->id;
+		
+		$text2 = 'XXXX';
+
+		$change = new Change();
+		$change->user_id = $this->user()->id;
+		$change->client_id = $this->clientId(2);
+		$change->item_type = BaseItem::enumId('type', 'note');
+		$change->item_field = 'body';
+		$change->type = Change::enumId('type', 'update');
+		$change->item_id = $itemId;
+		$change->previous_id = $changeId1;
+		$change->createDelta($text2);
+		$change->save();
+
+		$changeId2 = $change->id;
+
+		$text3 = 'YYYY';
+
+		$change = new Change();
+		$change->user_id = $this->user()->id;
+		$change->client_id = $this->clientId(1);
+		$change->item_type = BaseItem::enumId('type', 'note');
+		$change->item_field = 'body';
+		$change->type = Change::enumId('type', 'update');
+		$change->item_id = $itemId;
+		$change->previous_id = $changeId1;
+		$change->createDelta($text3);
+		$change->save();
+
+		$changeId3 = $change->id;
+
+		$r = Change::fullFieldText($itemId, 'body');
+
+		var_dump($r);die();
+
+		$this->assertEquals($r, 'cd CLIENT1 efgh ijkl FROMCLIENT2');		
+	}
+
 	public function testSame() {
 		$note = new Note();
 		$note->fromPublicArray(array('body' => 'test'));