diff --git a/workflow/engine/classes/model/map/SubProcessMapBuilder.php b/workflow/engine/classes/model/map/SubProcessMapBuilder.php
index 64a63c6a0..74f7bf69c 100644
--- a/workflow/engine/classes/model/map/SubProcessMapBuilder.php
+++ b/workflow/engine/classes/model/map/SubProcessMapBuilder.php
@@ -84,7 +84,7 @@ class SubProcessMapBuilder {
 
 		$tMap->addColumn('SP_VARIABLES_OUT', 'SpVariablesOut', 'string', CreoleTypes::LONGVARCHAR, true, null);
 
-		$tMap->addColumn('SP_VARIABLES_IN', 'SpVariablesIn', 'string', CreoleTypes::LONGVARCHAR, true, null);
+		$tMap->addColumn('SP_VARIABLES_IN', 'SpVariablesIn', 'string', CreoleTypes::LONGVARCHAR, false, null);
 
 		$tMap->addColumn('SP_GRID_IN', 'SpGridIn', 'string', CreoleTypes::VARCHAR, true, 50);
 
diff --git a/workflow/engine/config/schema.xml b/workflow/engine/config/schema.xml
index b66b849e8..0bdde9862 100644
--- a/workflow/engine/config/schema.xml
+++ b/workflow/engine/config/schema.xml
@@ -1891,7 +1891,7 @@
     <column name="SP_SYNCHRONOUS_TYPE" type="VARCHAR" size="20" required="true" default=""/>
     <column name="SP_SYNCHRONOUS_WAIT" type="INTEGER" required="true" default="0"/>
     <column name="SP_VARIABLES_OUT" type="LONGVARCHAR" required="true"/>
-    <column name="SP_VARIABLES_IN" type="LONGVARCHAR" required="true"/>
+    <column name="SP_VARIABLES_IN" type="LONGVARCHAR" required="false"/>
     <column name="SP_GRID_IN" type="VARCHAR" size="50" required="true" default=""/>
     <validator column="SP_TYPE">
       <rule name="validValues" value="SIMPLE|MULTIPLE" message="Please select a valid value for SP_TYPE."/>
diff --git a/workflow/engine/data/mysql/schema.sql b/workflow/engine/data/mysql/schema.sql
index 5906832c5..c256bcb79 100644
--- a/workflow/engine/data/mysql/schema.sql
+++ b/workflow/engine/data/mysql/schema.sql
@@ -865,7 +865,7 @@ CREATE TABLE `SUB_PROCESS`
 	`SP_SYNCHRONOUS_TYPE` VARCHAR(20) default '' NOT NULL,
 	`SP_SYNCHRONOUS_WAIT` INTEGER default 0 NOT NULL,
 	`SP_VARIABLES_OUT` MEDIUMTEXT  NOT NULL,
-	`SP_VARIABLES_IN` MEDIUMTEXT  NOT NULL,
+	`SP_VARIABLES_IN` MEDIUMTEXT,
 	`SP_GRID_IN` VARCHAR(50) default '' NOT NULL,
 	PRIMARY KEY (`SP_UID`),
 	KEY `indexSubProcess`(`PRO_UID`, `PRO_PARENT`)