diff --git a/doc/files.md b/doc/files.md
--- a/doc/files.md
+++ b/doc/files.md
@@ -18,6 +18,7 @@
 * wallets/wallet.dat: personal wallet (BDB) with keys and transactions; since 0.18.7
 * .cookie: session RPC authentication cookie (written at start when cookie authentication is used, deleted on shutdown): since 0.12.0
 * onion_private_key: cached Tor hidden service private key for `-listenonion`: since 0.12.0
+* guisettings.ini.bak: backup of former GUI settings after `-resetguisettings` is used
 
 Only used in pre-0.8.0
 ---------------------
diff --git a/src/qt/optionsmodel.cpp b/src/qt/optionsmodel.cpp
--- a/src/qt/optionsmodel.cpp
+++ b/src/qt/optionsmodel.cpp
@@ -192,9 +192,31 @@
     language = settings.value("language").toString();
 }
 
+/**
+ * Helper function to copy contents from one QSettings to another.
+ * By using allKeys this also covers nested settings in a hierarchy.
+ */
+static void CopySettings(QSettings &dst, const QSettings &src) {
+    for (const QString &key : src.allKeys()) {
+        dst.setValue(key, src.value(key));
+    }
+}
+
+/** Back up a QSettings to an ini-formatted file. */
+static void BackupSettings(const fs::path &filename, const QSettings &src) {
+    qWarning() << "Backing up GUI settings to"
+               << GUIUtil::boostPathToQString(filename);
+    QSettings dst(GUIUtil::boostPathToQString(filename), QSettings::IniFormat);
+    dst.clear();
+    CopySettings(dst, src);
+}
+
 void OptionsModel::Reset() {
     QSettings settings;
 
+    // Backup old settings to chain-specific datadir for troubleshooting
+    BackupSettings(GetDataDir(true) / "guisettings.ini.bak", settings);
+
     // Save the strDataDir setting
     QString dataDir = Intro::getDefaultDataDirectory();
     dataDir = settings.value("strDataDir", dataDir).toString();