diff --git a/doc/release-notes.md b/doc/release-notes.md
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -5,3 +5,6 @@
   <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
--- a/src/qt/askpassphrasedialog.cpp
+++ b/src/qt/askpassphrasedialog.cpp
@@ -207,7 +207,9 @@
             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() &&