Fixed v5 field value bug

CHANGELOG.md

@@ -18,6 +18,7 @@
 - Fixed a bug where system icons whose names ended in numbers weren’t displaying. ([#14740](https://github.com/craftcms/cms/issues/14740))
 - Fixed an error that could occur when creating a passkey. ([#14745](https://github.com/craftcms/cms/issues/14745))
 - Fixed a bug where the “Utilities” global nav item could get two badge counts.
+- Fixed a bug where custom fields whose previous types were missing would lose their values when updating to Craft 5.
 
 ## 5.0.0 - 2024-03-26
 

src/migrations/BaseContentRefactorMigration.php

@@ -8,6 +8,7 @@
 use craft\db\Query;
 use craft\db\Table;
 use craft\fieldlayoutelements\CustomField;
+use craft\fields\MissingField;
 use craft\helpers\ArrayHelper;
 use craft\helpers\Db;
 use craft\helpers\Json;
@@ -118,7 +119,13 @@ protected function updateElements(
 
             foreach ($fieldColumns as $layoutElementUid => $column) {
                 $field = $fieldsByUid[$layoutElementUid];
-                $dbType = $field::dbType();
+
+                if ($field instanceof MissingField) {
+                    // Figure it out from the actual DB column
+                    $dbType = $contentTableSchema->getColumn($column)?->dbType;
+                } else {
+                    $dbType = $field::dbType();
+                }
 
                 if (is_array($column)) {
                     /** @var array $dbType */