diff --git a/inc/field/actorfield.class.php b/inc/field/actorfield.class.php
index 8a9648bf0..dcf2c71e0 100644
--- a/inc/field/actorfield.class.php
+++ b/inc/field/actorfield.class.php
@@ -213,7 +213,7 @@ public function getValueForDesign(): string {
       return implode("\r\n", $value);
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $value = [];
       foreach ($this->value as $item) {
          if (filter_var($item, FILTER_VALIDATE_EMAIL) !== false) {
diff --git a/inc/field/checkboxesfield.class.php b/inc/field/checkboxesfield.class.php
index 8199bfda9..e45a6facd 100644
--- a/inc/field/checkboxesfield.class.php
+++ b/inc/field/checkboxesfield.class.php
@@ -276,7 +276,7 @@ public function hasInput($input): bool {
       return isset($input['formcreator_field_' . $this->question->getID()]);
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $value = [];
       $values = $this->getAvailableValues();
 
diff --git a/inc/field/datefield.class.php b/inc/field/datefield.class.php
index 775679797..2a48ee469 100644
--- a/inc/field/datefield.class.php
+++ b/inc/field/datefield.class.php
@@ -116,7 +116,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return Html::convDate($this->value);
    }
 
diff --git a/inc/field/datetimefield.class.php b/inc/field/datetimefield.class.php
index 2a8c1af2b..dfe130801 100644
--- a/inc/field/datetimefield.class.php
+++ b/inc/field/datetimefield.class.php
@@ -122,7 +122,7 @@ public function hasInput($input): bool {
       return isset($input['formcreator_field_' . $this->question->getID()]);
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return Html::convDateTime($this->value);
    }
 
diff --git a/inc/field/descriptionfield.class.php b/inc/field/descriptionfield.class.php
index ec8836a89..1486ab533 100644
--- a/inc/field/descriptionfield.class.php
+++ b/inc/field/descriptionfield.class.php
@@ -71,7 +71,7 @@ public function getValueForDesign(): string {
       return '';
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $text = $this->question->fields['description'];
       if (!$richText) {
          $text = nl2br(strip_tags(html_entity_decode($text)));
diff --git a/inc/field/dropdownfield.class.php b/inc/field/dropdownfield.class.php
index d4d33a0db..845a63204 100644
--- a/inc/field/dropdownfield.class.php
+++ b/inc/field/dropdownfield.class.php
@@ -412,7 +412,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $DbUtil = new DbUtils();
       $itemtype = $this->getSubItemtype();
       if ($itemtype == User::class) {
diff --git a/inc/field/filefield.class.php b/inc/field/filefield.class.php
index fdb80a656..0a167dfb4 100644
--- a/inc/field/filefield.class.php
+++ b/inc/field/filefield.class.php
@@ -101,7 +101,7 @@ public function getValueForDesign(): string {
       return '';
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return $this->value;
    }
 
diff --git a/inc/field/floatfield.class.php b/inc/field/floatfield.class.php
index 1c603865a..719ce780f 100644
--- a/inc/field/floatfield.class.php
+++ b/inc/field/floatfield.class.php
@@ -125,7 +125,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return $this->value;
    }
 
diff --git a/inc/field/hiddenfield.class.php b/inc/field/hiddenfield.class.php
index e352e69fe..86038e953 100644
--- a/inc/field/hiddenfield.class.php
+++ b/inc/field/hiddenfield.class.php
@@ -110,7 +110,7 @@ public static function getName(): string {
       return _n('Hidden field', 'Hidden fields', 1);
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return str_replace("\n", '\r\n', $this->value);
    }
 
diff --git a/inc/field/hostnamefield.class.php b/inc/field/hostnamefield.class.php
index e2fcd6e84..c74cac41e 100644
--- a/inc/field/hostnamefield.class.php
+++ b/inc/field/hostnamefield.class.php
@@ -87,7 +87,7 @@ public function getValueForDesign(): string {
       return '';
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return $this->value;
    }
 
diff --git a/inc/field/ipfield.class.php b/inc/field/ipfield.class.php
index 602569c2b..93ee71e7a 100644
--- a/inc/field/ipfield.class.php
+++ b/inc/field/ipfield.class.php
@@ -95,7 +95,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return $this->value;
    }
 
diff --git a/inc/field/radiosfield.class.php b/inc/field/radiosfield.class.php
index 58c5ee2d1..4ab1e4901 100644
--- a/inc/field/radiosfield.class.php
+++ b/inc/field/radiosfield.class.php
@@ -216,7 +216,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return $this->value;
    }
 
diff --git a/inc/field/requesttypefield.class.php b/inc/field/requesttypefield.class.php
index f1bbec33c..02819d4a5 100644
--- a/inc/field/requesttypefield.class.php
+++ b/inc/field/requesttypefield.class.php
@@ -170,7 +170,7 @@ public function hasInput($input): bool {
       return isset($input['formcreator_field_' . $this->question->getID()]);
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $available = $this->getAvailableValues();
       return $available[$this->value];
    }
diff --git a/inc/field/tagfield.class.php b/inc/field/tagfield.class.php
index ff2d3ed3a..bbe41f4a1 100644
--- a/inc/field/tagfield.class.php
+++ b/inc/field/tagfield.class.php
@@ -145,7 +145,7 @@ public function getValueForDesign(): string {
       return implode("\r\n", $this->value);
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $value = Dropdown::getDropdownName(PluginTagTag::getTable(), $this->value);
       return $value;
    }
diff --git a/inc/field/textareafield.class.php b/inc/field/textareafield.class.php
index e753097e4..a46e3d504 100644
--- a/inc/field/textareafield.class.php
+++ b/inc/field/textareafield.class.php
@@ -214,7 +214,7 @@ public function parseAnswerValues($input, $nonDestructive = false): bool {
       return true;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $value = $this->value;
       if (!$richText) {
          $value = Toolbox::unclean_cross_side_scripting_deep($value);
diff --git a/inc/field/textfield.class.php b/inc/field/textfield.class.php
index 4678a4e06..101b3f2c8 100644
--- a/inc/field/textfield.class.php
+++ b/inc/field/textfield.class.php
@@ -130,7 +130,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return $this->value;
    }
 
diff --git a/inc/field/timefield.class.php b/inc/field/timefield.class.php
index 9c45d4bef..3f326a003 100644
--- a/inc/field/timefield.class.php
+++ b/inc/field/timefield.class.php
@@ -117,7 +117,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $date = DateTime::createFromFormat("H:i:s", $this->value);
       if ($date === false) {
          return ' ';
diff --git a/inc/field/urgencyfield.class.php b/inc/field/urgencyfield.class.php
index 1fcaf5edb..f8cfa6533 100644
--- a/inc/field/urgencyfield.class.php
+++ b/inc/field/urgencyfield.class.php
@@ -174,7 +174,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       $available = $this->getAvailableValues();
       return $available[$this->value];
    }
diff --git a/inc/fieldinterface.class.php b/inc/fieldinterface.class.php
index 1deaabcd3..849f619c5 100644
--- a/inc/fieldinterface.class.php
+++ b/inc/fieldinterface.class.php
@@ -116,7 +116,7 @@ public function getValueForDesign() : string;
     *
     * @return string
     */
-   public function getValueForTargetText($richText) : string;
+   public function getValueForTargetText($richText): ?string;
 
    /**
     * Move uploaded files and make Document items
diff --git a/tests/fixture/PluginFormcreatorDependentField.php b/tests/fixture/PluginFormcreatorDependentField.php
index e1dd37149..5f88b7e1e 100644
--- a/tests/fixture/PluginFormcreatorDependentField.php
+++ b/tests/fixture/PluginFormcreatorDependentField.php
@@ -161,7 +161,7 @@ public function getValueForDesign(): string {
       return $this->value;
    }
 
-   public function getValueForTargetText($richText): string {
+   public function getValueForTargetText($richText): ?string {
       return Toolbox::addslashes_deep($this->value);
    }