diff --git a/api/src/Db.php b/api/src/Db.php
index 729fbd38a5..6c713c9fc3 100644
--- a/api/src/Db.php
+++ b/api/src/Db.php
@@ -822,6 +822,7 @@ class Db
 				if (in_array($e->getCode(), [
 					1064,   // You have an error in your SQL syntax
 					1062,   // Duplicate entry
+					1054,   // Unknown column 'X' in 'field list'
 				]))
 				{
 					throw new Db\Exception\InvalidSql($e->getMessage(), $e->getCode(), $e);
diff --git a/api/src/Db/Schema.php b/api/src/Db/Schema.php
index 8ec20f0a7c..9427a08ebb 100644
--- a/api/src/Db/Schema.php
+++ b/api/src/Db/Schema.php
@@ -1164,6 +1164,12 @@ class Schema
 					}
 					break;
 				case 'decimal':
+					// some old and broken backups have that for timestamps, as it's invalid anyway (scale < 0), we translate it to timestamp
+					if ($col_data['precision'] === -1 && empty($col_data['scale']))
+					{
+						$ado_col = 'T';
+						break;
+					}
 					$ado_col = "N($col_data[precision].$col_data[scale])";
 					break;
 				case 'double':
diff --git a/setup/inc/class.setup.inc.php b/setup/inc/class.setup.inc.php
index 81cef749c1..a584d00fbc 100644
--- a/setup/inc/class.setup.inc.php
+++ b/setup/inc/class.setup.inc.php
@@ -536,7 +536,7 @@ class setup
 					'app_name'		=> $appname,
 				], __LINE__, __FILE__);
 			}
-			catch (Api\Db\Exception\InvalidSql $e)
+			catch (Api\Db\Exception $e)
 			{
 				// ease update from pre 1.6 eg. 1.4 not having app_index, app_icon, app_icon_app columns
 				_egw_log_exception($e);