diff --git a/config-sample.ini b/config-sample.ini
index a18d940a4..bc88f6e1a 100644
--- a/config-sample.ini
+++ b/config-sample.ini
@@ -7,6 +7,6 @@ instanceName=
 port=8080
 # true for TLS/SSL/HTTPS (secure), false for HTTP (unsecure).
 https=false
-# path to certificate (run "bash generate-cert.sh" to generate self-signed certificate). Relevant only if https=true
+# path to certificate (run "bash bin/generate-cert.sh" to generate self-signed certificate). Relevant only if https=true
 certPath=
 keyPath=
diff --git a/src/public/javascripts/services/tree_utils.js b/src/public/javascripts/services/tree_utils.js
index 548c9fcc5..e708ff845 100644
--- a/src/public/javascripts/services/tree_utils.js
+++ b/src/public/javascripts/services/tree_utils.js
@@ -34,7 +34,12 @@ function getNotePath(node) {
 async function getNoteTitle(noteId, parentNoteId = null) {
     utils.assertArguments(noteId);
 
-    let {title} = await treeCache.getNote(noteId);
+    const note = await treeCache.getNote(noteId);
+    if (!note) {
+        return "[not found]";
+    }
+
+    let {title} = note;
 
     if (parentNoteId !== null) {
         const branch = await treeCache.getBranchByChildParent(noteId, parentNoteId);
diff --git a/src/routes/api/import.js b/src/routes/api/import.js
index 2e47b1956..5911ab45e 100644
--- a/src/routes/api/import.js
+++ b/src/routes/api/import.js
@@ -79,6 +79,9 @@ async function importTar(file, parentNoteId) {
     const noteIdMap = {};
 
     await importNotes(files, parentNoteId, noteIdMap);
+
+    // import might contain relations targeting notes which are not in the import
+    await attributeService.removeInvalidRelations();
 }
 
 function getFileName(name) {
diff --git a/src/services/attributes.js b/src/services/attributes.js
index 176678f11..949d1884f 100644
--- a/src/services/attributes.js
+++ b/src/services/attributes.js
@@ -77,11 +77,31 @@ async function getAttributeNames(type, nameLike) {
     return names;
 }
 
+async function removeInvalidRelations() {
+    const relations = await repository.getEntities(`
+      SELECT attributes.* 
+      FROM attributes 
+          LEFT JOIN notes AS sourceNote ON attributes.noteId = sourceNote.noteId
+          LEFT JOIN notes AS targetNote ON attributes.value = targetNote.noteId
+      WHERE 
+          attributes.isDeleted = 0
+          AND attributes.type = 'relation'
+          AND (sourceNote.noteId IS NULL OR sourceNote.isDeleted
+               OR targetNote.noteId IS NULL OR targetNote.isDeleted)`);
+
+    for (const relation of relations) {
+        relation.isDeleted = true;
+
+        await relation.save();
+    }
+}
+
 module.exports = {
     getNotesWithLabel,
     getNoteWithLabel,
     createLabel,
     createAttribute,
     getAttributeNames,
+    removeInvalidRelations,
     BUILTIN_ATTRIBUTES
 };
\ No newline at end of file
diff --git a/src/services/notes.js b/src/services/notes.js
index abb1baf62..de27966f9 100644
--- a/src/services/notes.js
+++ b/src/services/notes.js
@@ -250,6 +250,11 @@ async function deleteNote(branch) {
         for (const childBranch of await note.getChildBranches()) {
             await deleteNote(childBranch);
         }
+
+        for (const attribute of await note.getOwnedAttributes()) {
+            attribute.isDeleted = true;
+            await attribute.save();
+        }
     }
 }