@@ -, +, @@ 
---
 .../data/mysql/atomicupdate/bug_21065.perl    | 22 +++++++++++--------
 installer/data/mysql/kohastructure.sql        |  2 +-
 2 files changed, 14 insertions(+), 10 deletions(-)
--- a/installer/data/mysql/atomicupdate/bug_21065.perl	
+++ a/installer/data/mysql/atomicupdate/bug_21065.perl	
@@ -1,15 +1,19 @@ 
 $DBversion = 'XXX';  # will be replaced by the RM
 if( CheckVersion( $DBversion ) ) {
 
-    $dbh->do(q|
-        ALTER TABLE accountlines DROP FOREIGN KEY accountlines_ibfk_1;
-    |);
-    $dbh->do(q|
-        ALTER TABLE accountlines CHANGE COLUMN borrowernumber borrowernumber INT(11) DEFAULT NULL;
-    |);
-    $dbh->do(q|
-        ALTER TABLE accountlines ADD CONSTRAINT accountlines_ibfk_1 FOREIGN KEY (borrowernumber) REFERENCES borrowers (borrowernumber) ON DELETE SET NULL ON UPDATE CASCADE;
-    |);
+    my $sth = $dbh->prepare(q|SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE CONSTRAINT_NAME='accountlines_ibfk_1'|);
+    $sth->execute;
+    if ($sth->fetchrow_hashref) {
+        $dbh->do(q|
+            ALTER TABLE accountlines DROP FOREIGN KEY accountlines_ibfk_1;
+        |);
+        $dbh->do(q|
+            ALTER TABLE accountlines CHANGE COLUMN borrowernumber borrowernumber INT(11) DEFAULT NULL;
+        |);
+        $dbh->do(q|
+            ALTER TABLE accountlines ADD CONSTRAINT accountlines_ibfk_borrowers FOREIGN KEY (borrowernumber) REFERENCES borrowers (borrowernumber) ON DELETE SET NULL ON UPDATE CASCADE;
+        |);
+    }
 
     SetVersion( $DBversion );
     print "Upgrade to $DBversion done (Bug 21065 - Set ON DELETE SET NULL on accountlines.borrowernumber)\n";
--- a/installer/data/mysql/kohastructure.sql	
+++ a/installer/data/mysql/kohastructure.sql	
@@ -2722,7 +2722,7 @@ CREATE TABLE `accountlines` (
   KEY `acctsborridx` (`borrowernumber`),
   KEY `timeidx` (`timestamp`),
   KEY `itemnumber` (`itemnumber`),
-  CONSTRAINT `accountlines_ibfk_1` FOREIGN KEY (`borrowernumber`) REFERENCES `borrowers` (`borrowernumber`) ON DELETE SET NULL ON UPDATE CASCADE,
+  CONSTRAINT `accountlines_ibfk_borrowers` FOREIGN KEY (`borrowernumber`) REFERENCES `borrowers` (`borrowernumber`) ON DELETE SET NULL ON UPDATE CASCADE,
   CONSTRAINT `accountlines_ibfk_2` FOREIGN KEY (`itemnumber`) REFERENCES `items` (`itemnumber`) ON DELETE SET NULL ON UPDATE SET NULL
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
--