diff --git a/doc/release-notes.md b/doc/release-notes.md
index 054bca19e..59336466d 100644
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -1,7 +1,10 @@
 # Bitcoin ABC 0.24.10 Release Notes
 
 Bitcoin ABC version 0.24.10 is now available from:
 
   <https://download.bitcoinabc.org/0.24.10/>
 
 This release includes the following features and fixes:
+ - Fix a bug introduced in version 0.24.7 that caused the "OK" button to stay
+   disabled in the GUI's passphrase dialog when sending a transaction from an
+   encrypted wallet.
diff --git a/src/qt/askpassphrasedialog.cpp b/src/qt/askpassphrasedialog.cpp
index a3c8c7a81..0080ad543 100644
--- a/src/qt/askpassphrasedialog.cpp
+++ b/src/qt/askpassphrasedialog.cpp
@@ -1,280 +1,282 @@
 // Copyright (c) 2011-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <qt/askpassphrasedialog.h>
 #include <qt/forms/ui_askpassphrasedialog.h>
 
 #include <qt/guiconstants.h>
 #include <qt/guiutil.h>
 #include <qt/walletmodel.h>
 #include <support/allocators/secure.h>
 
 #include <QKeyEvent>
 #include <QMessageBox>
 #include <QPushButton>
 
 AskPassphraseDialog::AskPassphraseDialog(Mode _mode, QWidget *parent,
                                          SecureString *passphrase_out)
     : QDialog(parent), ui(new Ui::AskPassphraseDialog), mode(_mode),
       model(nullptr), fCapsLock(false), m_passphrase_out(passphrase_out) {
     ui->setupUi(this);
 
     ui->passEdit1->setMinimumSize(ui->passEdit1->sizeHint());
     ui->passEdit2->setMinimumSize(ui->passEdit2->sizeHint());
     ui->passEdit3->setMinimumSize(ui->passEdit3->sizeHint());
 
     ui->passEdit1->setMaxLength(MAX_PASSPHRASE_SIZE);
     ui->passEdit2->setMaxLength(MAX_PASSPHRASE_SIZE);
     ui->passEdit3->setMaxLength(MAX_PASSPHRASE_SIZE);
 
     // Setup Caps Lock detection.
     ui->passEdit1->installEventFilter(this);
     ui->passEdit2->installEventFilter(this);
     ui->passEdit3->installEventFilter(this);
 
     switch (mode) {
         case Encrypt: // Ask passphrase x2
             ui->warningLabel->setText(
                 tr("Enter the new passphrase for the wallet.<br/>Please use a "
                    "passphrase of <b>ten or more random characters</b>, or "
                    "<b>eight or more words</b>."));
             ui->passLabel1->hide();
             ui->passEdit1->hide();
             setWindowTitle(tr("Encrypt wallet"));
             break;
         case Unlock: // Ask passphrase
             ui->warningLabel->setText(tr("This operation needs your wallet "
                                          "passphrase to unlock the wallet."));
             ui->passLabel2->hide();
             ui->passEdit2->hide();
             ui->passLabel3->hide();
             ui->passEdit3->hide();
             setWindowTitle(tr("Unlock wallet"));
             break;
         case ChangePass: // Ask old passphrase + new passphrase x2
             setWindowTitle(tr("Change passphrase"));
             ui->warningLabel->setText(tr(
                 "Enter the old passphrase and new passphrase for the wallet."));
             break;
     }
     textChanged();
     connect(ui->toggleShowPasswordButton, &QPushButton::toggled, this,
             &AskPassphraseDialog::toggleShowPassword);
     connect(ui->passEdit1, &QLineEdit::textChanged, this,
             &AskPassphraseDialog::textChanged);
     connect(ui->passEdit2, &QLineEdit::textChanged, this,
             &AskPassphraseDialog::textChanged);
     connect(ui->passEdit3, &QLineEdit::textChanged, this,
             &AskPassphraseDialog::textChanged);
 
     GUIUtil::handleCloseWindowShortcut(this);
 }
 
 AskPassphraseDialog::~AskPassphraseDialog() {
     secureClearPassFields();
     delete ui;
 }
 
 void AskPassphraseDialog::setModel(WalletModel *_model) {
     this->model = _model;
 }
 
 void AskPassphraseDialog::accept() {
     SecureString oldpass, newpass1, newpass2;
     if (!model && mode != Encrypt) {
         return;
     }
     oldpass.reserve(MAX_PASSPHRASE_SIZE);
     newpass1.reserve(MAX_PASSPHRASE_SIZE);
     newpass2.reserve(MAX_PASSPHRASE_SIZE);
     // TODO: get rid of this .c_str() by implementing
     // SecureString::operator=(std::string)
     // Alternately, find a way to make this input mlock()'d to begin with.
     oldpass.assign(ui->passEdit1->text().toStdString().c_str());
     newpass1.assign(ui->passEdit2->text().toStdString().c_str());
     newpass2.assign(ui->passEdit3->text().toStdString().c_str());
 
     secureClearPassFields();
 
     switch (mode) {
         case Encrypt: {
             if (newpass1.empty() || newpass2.empty()) {
                 // Cannot encrypt with empty passphrase
                 break;
             }
             QMessageBox::StandardButton retval = QMessageBox::question(
                 this, tr("Confirm wallet encryption"),
                 tr("Warning: If you encrypt your wallet and lose your "
                    "passphrase, you will <b>LOSE ALL OF YOUR BITCOINS</b>!") +
                     "<br><br>" +
                     tr("Are you sure you wish to encrypt your wallet?"),
                 QMessageBox::Yes | QMessageBox::Cancel, QMessageBox::Cancel);
             if (retval == QMessageBox::Yes) {
                 if (newpass1 == newpass2) {
                     QString encryption_reminder =
                         tr("Remember that encrypting your wallet cannot fully "
                            "protect your bitcoins from being stolen by malware "
                            "infecting your computer.");
                     if (m_passphrase_out) {
                         m_passphrase_out->assign(newpass1);
                         QMessageBox::warning(
                             this, tr("Wallet to be encrypted"),
                             "<qt>" +
                                 tr("Your wallet is about to be encrypted. ") +
                                 encryption_reminder + "</b></qt>");
                     } else {
                         assert(model != nullptr);
                         if (model->setWalletEncrypted(newpass1)) {
                             QMessageBox::warning(
                                 this, tr("Wallet encrypted"),
                                 "<qt>" + tr("Your wallet is now encrypted. ") +
                                     encryption_reminder + "<br><br><b>" +
                                     tr("IMPORTANT: Any previous backups you "
                                        "have made of your wallet file should "
                                        "be replaced with the newly generated, "
                                        "encrypted wallet file. For security "
                                        "reasons, previous backups of the "
                                        "unencrypted wallet file will become "
                                        "useless as soon as you start using the "
                                        "new, encrypted wallet.") +
                                     "</b></qt>");
                         } else {
                             QMessageBox::critical(
                                 this, tr("Wallet encryption failed"),
                                 tr("Wallet encryption failed due to an "
                                    "internal error. Your wallet was not "
                                    "encrypted."));
                         }
                     }
                     QDialog::accept(); // Success
                 } else {
                     QMessageBox::critical(
                         this, tr("Wallet encryption failed"),
                         tr("The supplied passphrases do not match."));
                 }
             } else {
                 QDialog::reject(); // Cancelled
             }
         } break;
         case Unlock:
             try {
                 if (!model->setWalletLocked(false, oldpass)) {
                     QMessageBox::critical(
                         this, tr("Wallet unlock failed"),
                         tr("The passphrase entered for the wallet decryption "
                            "was incorrect."));
                 } else {
                     // Success
                     QDialog::accept();
                 }
             } catch (const std::runtime_error &e) {
                 QMessageBox::critical(this, tr("Wallet unlock failed"),
                                       e.what());
             }
             break;
         case ChangePass:
             if (newpass1 == newpass2) {
                 if (model->changePassphrase(oldpass, newpass1)) {
                     QMessageBox::information(
                         this, tr("Wallet encrypted"),
                         tr("Wallet passphrase was successfully changed."));
                     QDialog::accept(); // Success
                 } else {
                     QMessageBox::critical(
                         this, tr("Wallet encryption failed"),
                         tr("The passphrase entered for the wallet decryption "
                            "was incorrect."));
                 }
             } else {
                 QMessageBox::critical(
                     this, tr("Wallet encryption failed"),
                     tr("The supplied passphrases do not match."));
             }
             break;
     }
 }
 
 void AskPassphraseDialog::textChanged() {
     // Validate input, set Ok button to enabled when acceptable
     bool acceptable = false;
     switch (mode) {
         case Encrypt: // New passphrase x2
             acceptable = !ui->passEdit2->text().isEmpty() &&
                          !ui->passEdit3->text().isEmpty();
             break;
-        case Unlock:     // Old passphrase x1
+        case Unlock: // Old passphrase x1
+            acceptable = !ui->passEdit1->text().isEmpty();
+            break;
         case ChangePass: // Old passphrase x1, new passphrase x2
             acceptable = !ui->passEdit1->text().isEmpty() &&
                          !ui->passEdit2->text().isEmpty() &&
                          !ui->passEdit3->text().isEmpty();
             break;
     }
     ui->buttonBox->button(QDialogButtonBox::Ok)->setEnabled(acceptable);
 }
 
 bool AskPassphraseDialog::event(QEvent *event) {
     // Detect Caps Lock key press.
     if (event->type() == QEvent::KeyPress) {
         QKeyEvent *ke = static_cast<QKeyEvent *>(event);
         if (ke->key() == Qt::Key_CapsLock) {
             fCapsLock = !fCapsLock;
         }
         if (fCapsLock) {
             ui->capsLabel->setText(tr("Warning: The Caps Lock key is on!"));
         } else {
             ui->capsLabel->clear();
         }
     }
     return QWidget::event(event);
 }
 
 void AskPassphraseDialog::toggleShowPassword(bool show) {
     ui->toggleShowPasswordButton->setDown(show);
     const auto renderingMode = show ? QLineEdit::Normal : QLineEdit::Password;
     ui->passEdit1->setEchoMode(renderingMode);
     ui->passEdit2->setEchoMode(renderingMode);
     ui->passEdit3->setEchoMode(renderingMode);
 }
 
 bool AskPassphraseDialog::eventFilter(QObject *object, QEvent *event) {
     /* Detect Caps Lock.
      * There is no good OS-independent way to check a key state in Qt, but
      * we can detect Caps Lock by checking for the following condition:
      * Shift key is down and the result is a lower case character, or
      * Shift key is not down and the result is an upper case character.
      */
     if (event->type() == QEvent::KeyPress) {
         QKeyEvent *ke = static_cast<QKeyEvent *>(event);
         QString str = ke->text();
         if (str.length() != 0) {
             const QChar *psz = str.unicode();
             bool fShift = (ke->modifiers() & Qt::ShiftModifier) != 0;
             if ((fShift && *psz >= 'a' && *psz <= 'z') ||
                 (!fShift && *psz >= 'A' && *psz <= 'Z')) {
                 fCapsLock = true;
                 ui->capsLabel->setText(tr("Warning: The Caps Lock key is on!"));
             } else if (psz->isLetter()) {
                 fCapsLock = false;
                 ui->capsLabel->clear();
             }
         }
     }
     return QDialog::eventFilter(object, event);
 }
 
 static void SecureClearQLineEdit(QLineEdit *edit) {
     // Attempt to overwrite text so that they do not linger around in memory
     edit->setText(QString(" ").repeated(edit->text().size()));
     edit->clear();
 }
 
 void AskPassphraseDialog::secureClearPassFields() {
     SecureClearQLineEdit(ui->passEdit1);
     SecureClearQLineEdit(ui->passEdit2);
     SecureClearQLineEdit(ui->passEdit3);
 }