diff --git a/src/org/omegat/Bundle.properties b/src/org/omegat/Bundle.properties
index b1848b08dd..2bfe302ad7 100644
--- a/src/org/omegat/Bundle.properties
+++ b/src/org/omegat/Bundle.properties
@@ -2326,6 +2326,7 @@ TEAM_26_to_36_CONVERT_FAILED=Project conversion failed.\n\
 TEAM_USERPASS_TITLE=Authentication
 TEAM_USERPASS_FIRST=Enter your credentials for {0}
 TEAM_USERPASS_WRONG=Incorrect username/password for {0}
+TEAM_USERPASS_EXTRA_SPACE=Username or password has extra space character(s)
 TEAM_USER_FIRST=Enter the username for {0}
 TEAM_PASS_FIRST=Enter the password for {0}
 TEAM_PASSPHRASE_FIRST=Enter the passphrase for SSH key {0}
diff --git a/src/org/omegat/core/team2/gui/UserPassDialog.java b/src/org/omegat/core/team2/gui/UserPassDialog.java
index 8f7b29dcbc..43475f235c 100644
--- a/src/org/omegat/core/team2/gui/UserPassDialog.java
+++ b/src/org/omegat/core/team2/gui/UserPassDialog.java
@@ -28,12 +28,14 @@
 package org.omegat.core.team2.gui;
 
 import java.awt.BorderLayout;
+import java.awt.Color;
 import java.awt.Dimension;
 import java.awt.GridBagConstraints;
 import java.awt.event.ActionEvent;
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
 
+import javax.swing.Action;
 import javax.swing.JButton;
 import javax.swing.JCheckBox;
 import javax.swing.JLabel;
@@ -41,6 +43,8 @@
 import javax.swing.JPasswordField;
 import javax.swing.JTextArea;
 import javax.swing.JTextField;
+import javax.swing.event.DocumentEvent;
+import javax.swing.event.DocumentListener;
 
 import org.omegat.util.OStrings;
 import org.omegat.util.gui.StaticUIUtils;
@@ -66,6 +70,7 @@ public UserPassDialog(java.awt.Frame parent) {
 
         initComponents();
         getRootPane().setDefaultButton(okButton);
+        setActions();
 
         invalidate();
         pack();
@@ -74,6 +79,60 @@ public UserPassDialog(java.awt.Frame parent) {
         usernameField.requestFocusInWindow();
     }
 
+    private void setActions() {
+        usernameField.getDocument().addDocumentListener(new DocumentListener() {
+            @Override
+            public void insertUpdate(DocumentEvent e) {
+                checkCredentials();
+            }
+
+            @Override
+            public void removeUpdate(DocumentEvent e) {
+                checkCredentials();
+            }
+
+            @Override
+            public void changedUpdate(DocumentEvent e) {
+                checkCredentials();
+            }
+        });
+        passwordField.getDocument().addDocumentListener(new DocumentListener() {
+            @Override
+            public void insertUpdate(DocumentEvent e) {
+                checkCredentials();
+            }
+
+            @Override
+            public void removeUpdate(DocumentEvent e) {
+                checkCredentials();
+            }
+
+            @Override
+            public void changedUpdate(DocumentEvent e) {
+                checkCredentials();
+            }
+        });
+    }
+
+    private void checkCredentials() {
+        String username = usernameField.getText();
+        char[] password = passwordField.getPassword();
+        boolean isValid = !username.trim().isEmpty() && password.length > 0;
+
+        if (isValid) {
+            isValid = username.trim().length() == username.length() && password[0] != ' '
+                    && password[password.length - 1] != ' ';
+            if (!isValid) {
+                setMessage(OStrings.getString("TEAM_USERPASS_EXTRA_SPACE"));
+            }
+        }
+        if (isValid) {
+            resetMessage();
+        }
+
+        okButton.setEnabled(isValid);
+    }
+
     /**
      * @return the return status of this dialog - one of RET_OK or RET_CANCEL
      */
@@ -88,7 +147,7 @@ private void initComponents() {
         GridBagConstraints gridBagConstraints;
 
         JPanel northPanel = new JPanel();
-        JPanel mainPanel = new JPanel();
+        mainPanel = new JPanel();
         JPanel buttonPanel = new JPanel();
         JPanel southPanel = new JPanel();
         descriptionTextArea = new JTextArea();
@@ -97,6 +156,7 @@ private void initComponents() {
         JLabel passwordLabel = new JLabel();
         passwordField = new JPasswordField();
         perHostCheckBox = new JCheckBox();
+        messageArea = new JTextArea();
         okButton = new JButton();
         JButton cancelButton = new JButton();
 
@@ -172,6 +232,16 @@ public void windowClosing(WindowEvent evt) {
         gridBagConstraints.insets = new java.awt.Insets(4, 16, 4, 4);
         mainPanel.add(perHostCheckBox, gridBagConstraints);
 
+        gridBagConstraints = new GridBagConstraints();
+        gridBagConstraints.gridx = 0;
+        gridBagConstraints.gridy = 8;
+        gridBagConstraints.gridwidth = 2;
+        gridBagConstraints.fill = GridBagConstraints.HORIZONTAL;
+        gridBagConstraints.anchor = GridBagConstraints.WEST;
+        gridBagConstraints.insets = new java.awt.Insets(4, 16, 4, 4);
+        messageArea.setBackground(mainPanel.getBackground());
+        mainPanel.add(messageArea, gridBagConstraints);
+
         getContentPane().add(mainPanel, BorderLayout.CENTER);
 
         southPanel.setBorder(javax.swing.BorderFactory.createEmptyBorder(10, 10, 10, 10));
@@ -210,11 +280,13 @@ private void doClose(int retStatus) {
         dispose();
     }
 
+    private JPanel mainPanel;
     private JButton okButton;
     private JTextArea descriptionTextArea;
     private JTextField usernameField;
     private JPasswordField passwordField;
-    private javax.swing.JCheckBox perHostCheckBox;
+    private JCheckBox perHostCheckBox;
+    private JTextArea messageArea;
 
     private int returnStatus = RET_CANCEL;
 
@@ -246,4 +318,14 @@ public void setDescription(String description) {
     public void setPerHostCheckBoxText(String text) {
         org.openide.awt.Mnemonics.setLocalizedText(perHostCheckBox, text);
     }
+
+    public void setMessage(String text) {
+        messageArea.setText(text);
+        messageArea.setBackground(Color.red);
+    }
+
+    public void resetMessage() {
+        messageArea.setText("");
+        messageArea.setBackground(mainPanel.getBackground());
+    }
 }