Getting an error when trying to log into Admin when `twofactorauth` is enabled

Question

When I have create a user via the CLI, I am unable to log into the Magento Admin because there is an error.

Fatal error: Uncaught TypeError: Return value of MSP\TwoFactorAuth\Model\ResourceModel\UserConfig::decodeConfig() must be of the type array, null returned in vendor/msp/twofactorauth/Model/ResourceModel/UserConfig.php on line 96

Answer 1

This issue is caused by the users encoded_config and encoded_providers being empty. Which in turn can't be unserialized which causes an empty response. The code expects an array.

To resolve this issue.

1. Make sure you have: cweagans/composer-patches installed. If not this can be installed with composer require cweagans/composer-patches
2. Add the following in your composer.json

...
"extra": {
    ...
    "composer-exit-on-patch-failure": true,
    "patches": {
        "msp/twofactorauth": {
            "Empty config error": "patches/msp_mfa_no_config_error_fix.patch"
        }
    }
},

3. make the following file: patches/msp_mfa_no_config_error_fix.patch

--- Model/ResourceModel/UserConfig.php    2020-06-19 11:30:47.611900565 +0000
+++ Model/ResourceModel/UserConfig.php 2020-06-19 11:38:47.911245449 +0000
@@ -99,18 +99,26 @@
   public function _afterLoad(AbstractModel $object)
   {
       parent::_afterLoad($object);
-
-        try {
-            $object->setData('config', $this->decodeConfig($object->getData('encoded_config') ?? ''));
-        } catch (Exception $e) {
-            $object->setData('config', []);
-        }
-
-        try {
-            $object->setData('providers', $this->serializer->unserialize($object->getData('encoded_providers') ?? ''));
-        } catch (Exception $e) {
-            $object->setData('providers', []);
+        
+        $config = [];
+        if($object->hasData('encoded_config')){
+               try{
+                       $config = $this->decodeConfig($object->getData('encoded_config') ?? '');
+               } catch (Exception $e) {
+                       // don't need to do anything should fall back to empty []
+               }
       }
+        $object->setData('config', $config);
+        
+        $providers = [];
+        if($object->hasData('encoded_providers')){
+            try {
+                $providers = $this->serializer->unserialize($object->getData('encoded_providers') ?? '');
+            } catch (Exception $e) {
+                // don't need to do anything should fall back to empty []
+            }
+        }
+        $object->setData('providers', $providers);

       return $this;
   }

5. composer update
6. rm -rf vendor/msp/twofactorauth
7. composer install --no-dev