diff --git a/src/applications/diffusion/panel/DiffusionSetPasswordPanel.php b/src/applications/diffusion/panel/DiffusionSetPasswordPanel.php
index c45acb7185..21e00c7076 100644
--- a/src/applications/diffusion/panel/DiffusionSetPasswordPanel.php
+++ b/src/applications/diffusion/panel/DiffusionSetPasswordPanel.php
@@ -74,16 +74,23 @@ final class DiffusionSetPasswordPanel extends PhabricatorSettingsPanel {
       if (!$errors) {
         $envelope = new PhutilOpaqueEnvelope($new_password);
 
+        try {
+          // NOTE: This test is against $viewer (not $user), so that the error
+          // message below makes sense in the case that the two are different,
+          // and because an admin reusing their own password is bad, while
+          // system agents generally do not have passwords anyway.
+
+          $same_password = $viewer->comparePassword($envelope);
+        } catch (PhabricatorPasswordHasherUnavailableException $ex) {
+          // If we're missing the hasher, just let the user continue.
+          $same_password = false;
+        }
+
         if ($new_password !== $confirm) {
           $e_password = pht('Does Not Match');
           $e_confirm = pht('Does Not Match');
           $errors[] = pht('Password and confirmation do not match.');
-        } else if ($viewer->comparePassword($envelope)) {
-          // NOTE: The above test is against $viewer (not $user), so that the
-          // error message below makes sense in the case that the two are
-          // different, and because an admin reusing their own password is bad,
-          // while system agents generally do not have passwords anyway.
-
+        } else if ($same_password) {
           $e_password = pht('Not Unique');
           $e_confirm = pht('Not Unique');
           $errors[] = pht(
@@ -197,7 +204,22 @@ final class DiffusionSetPasswordPanel extends PhabricatorSettingsPanel {
         ->setValue(PhabricatorPasswordHasher::getBestAlgorithmName()));
 
     if (strlen($hash_envelope->openEnvelope())) {
-      if (PhabricatorPasswordHasher::canUpgradeHash($hash_envelope)) {
+      try {
+        $can_upgrade = PhabricatorPasswordHasher::canUpgradeHash(
+          $hash_envelope);
+      } catch (PhabricatorPasswordHasherUnavailableException $ex) {
+        $can_upgrade = false;
+        $errors[] = pht(
+          'Your VCS password is currently hashed using an algorithm which is '.
+          'no longer available on this install.');
+        $errors[] = pht(
+          'Because the algorithm implementation is missing, your password '.
+          'can not be used.');
+        $errors[] = pht(
+          'You can set a new password to replace the old password.');
+      }
+
+      if ($can_upgrade) {
         $errors[] = pht(
           'The strength of your stored VCS password hash can be upgraded. '.
           'To upgrade, either: use the password to authenticate with a '.
diff --git a/src/applications/settings/panel/PhabricatorSettingsPanelPassword.php b/src/applications/settings/panel/PhabricatorSettingsPanelPassword.php
index 2aef196b96..eeb9b3410e 100644
--- a/src/applications/settings/panel/PhabricatorSettingsPanelPassword.php
+++ b/src/applications/settings/panel/PhabricatorSettingsPanelPassword.php
@@ -126,7 +126,28 @@ final class PhabricatorSettingsPanelPassword
 
     $hash_envelope = new PhutilOpaqueEnvelope($user->getPasswordHash());
     if (strlen($hash_envelope->openEnvelope())) {
-      if (PhabricatorPasswordHasher::canUpgradeHash($hash_envelope)) {
+      try {
+        $can_upgrade = PhabricatorPasswordHasher::canUpgradeHash(
+          $hash_envelope);
+      } catch (PhabricatorPasswordHasherUnavailableException $ex) {
+        $can_upgrade = false;
+
+        // Only show this stuff if we aren't on the reset workflow. We can
+        // do resets regardless of the old hasher's availability.
+        if (!$token) {
+          $errors[] = pht(
+            'Your password is currently hashed using an algorithm which is '.
+            'no longer available on this install.');
+          $errors[] = pht(
+            'Because the algorithm implementation is missing, your password '.
+            'can not be used or updated.');
+          $errors[] = pht(
+            'To set a new password, request a password reset link from the '.
+            'login screen and then follow the instructions.');
+        }
+      }
+
+      if ($can_upgrade) {
         $errors[] = pht(
           'The strength of your stored password hash can be upgraded. '.
           'To upgrade, either: log out and log in using your password; or '.
diff --git a/src/infrastructure/util/password/PhabricatorPasswordHasher.php b/src/infrastructure/util/password/PhabricatorPasswordHasher.php
index 338a7615ee..4409163509 100644
--- a/src/infrastructure/util/password/PhabricatorPasswordHasher.php
+++ b/src/infrastructure/util/password/PhabricatorPasswordHasher.php
@@ -407,7 +407,9 @@ abstract class PhabricatorPasswordHasher extends Phobject {
       $current_hasher = PhabricatorPasswordHasher::getHasherForHash($hash);
       return $current_hasher->getHumanReadableName();
     } catch (Exception $ex) {
-      return pht('Unknown');
+      $info = self::parseHashFromStorage($hash);
+      $name = $info['name'];
+      return pht('Unknown ("%s")', $name);
     }
   }