diff --git a/src/zcl_excel_reader_huge_file.clas.abap b/src/zcl_excel_reader_huge_file.clas.abap
index 714402e..e21d7a0 100644
--- a/src/zcl_excel_reader_huge_file.clas.abap
+++ b/src/zcl_excel_reader_huge_file.clas.abap
@@ -54,7 +54,8 @@ CLASS zcl_excel_reader_huge_file DEFINITION
       RETURNING
         VALUE(es_cell) TYPE t_cell
       RAISING
-        lcx_not_found .
+        lcx_not_found
+        zcx_excel .
     METHODS read_shared_strings
       IMPORTING
         !io_reader               TYPE REF TO if_sxml_reader
@@ -64,7 +65,9 @@ CLASS zcl_excel_reader_huge_file DEFINITION
       IMPORTING
         !iv_coord       TYPE string
       RETURNING
-        VALUE(es_coord) TYPE t_cell_coord .
+        VALUE(es_coord) TYPE t_cell_coord
+      RAISING
+        zcx_excel .
     METHODS put_cell_to_worksheet
       IMPORTING
         !io_worksheet TYPE REF TO zcl_excel_worksheet
diff --git a/src/zcl_excel_theme_color_scheme.clas.abap b/src/zcl_excel_theme_color_scheme.clas.abap
index ade6ee9..5da3f62 100644
--- a/src/zcl_excel_theme_color_scheme.clas.abap
+++ b/src/zcl_excel_theme_color_scheme.clas.abap
@@ -100,7 +100,7 @@ CLASS zcl_excel_theme_color_scheme IMPLEMENTATION.
                                                                parent = lo_elements ).
       lo_scheme_element->set_attribute( name = c_name value = name ).
 
-      "! Adding colors to scheme
+      " Adding colors to scheme
       lo_color ?= io_document->create_simple_element_ns( prefix = zcl_excel_theme=>c_theme_prefix
                                                                   name   = c_dark1
                                                       parent = lo_scheme_element ).
diff --git a/src/zcl_excel_theme_eclrschemelst.clas.abap b/src/zcl_excel_theme_eclrschemelst.clas.abap
index 2fc41e1..e3c1509 100644
--- a/src/zcl_excel_theme_eclrschemelst.clas.abap
+++ b/src/zcl_excel_theme_eclrschemelst.clas.abap
@@ -41,7 +41,7 @@ CLASS zcl_excel_theme_eclrschemelst IMPLEMENTATION.
 
 
   METHOD load.
-    "! so far copy only existing values
+    " so far copy only existing values
     extracolor ?= io_extra_color.
   ENDMETHOD.                    "load
 ENDCLASS.
diff --git a/src/zcl_excel_theme_extlst.clas.abap b/src/zcl_excel_theme_extlst.clas.abap
index b22209c..5120fcb 100644
--- a/src/zcl_excel_theme_extlst.clas.abap
+++ b/src/zcl_excel_theme_extlst.clas.abap
@@ -41,7 +41,7 @@ CLASS zcl_excel_theme_extlst IMPLEMENTATION.
 
 
   METHOD load.
-    "! so far copy only existing values
+    " so far copy only existing values
     extlst ?= io_extlst.
   ENDMETHOD.                    "load
 ENDCLASS.
diff --git a/src/zcl_excel_theme_fmt_scheme.clas.abap b/src/zcl_excel_theme_fmt_scheme.clas.abap
index 4923839..56c8625 100644
--- a/src/zcl_excel_theme_fmt_scheme.clas.abap
+++ b/src/zcl_excel_theme_fmt_scheme.clas.abap
@@ -189,7 +189,7 @@ CLASS zcl_excel_theme_fmt_scheme IMPLEMENTATION.
 
 
   METHOD load.
-    "! so far copy only existing values
+    " so far copy only existing values
     fmt_scheme ?= io_fmt_scheme.
   ENDMETHOD.                    "load
 ENDCLASS.
diff --git a/src/zcl_excel_theme_objectdefaults.clas.abap b/src/zcl_excel_theme_objectdefaults.clas.abap
index b00b45f..645e047 100644
--- a/src/zcl_excel_theme_objectdefaults.clas.abap
+++ b/src/zcl_excel_theme_objectdefaults.clas.abap
@@ -39,7 +39,7 @@ CLASS zcl_excel_theme_objectdefaults IMPLEMENTATION.
 
 
   METHOD load.
-    "! so far copy only existing values
+    " so far copy only existing values
     objectdefaults ?= io_object_def.
   ENDMETHOD.                    "load
 ENDCLASS.
diff --git a/src/zcl_excel_worksheet.clas.abap b/src/zcl_excel_worksheet.clas.abap
index b0f5373..546f54e 100644
--- a/src/zcl_excel_worksheet.clas.abap
+++ b/src/zcl_excel_worksheet.clas.abap
@@ -356,10 +356,14 @@ CLASS zcl_excel_worksheet DEFINITION
         zcx_excel .
     METHODS get_columns
       RETURNING
-        VALUE(eo_columns) TYPE REF TO zcl_excel_columns .
+        VALUE(eo_columns) TYPE REF TO zcl_excel_columns
+      RAISING
+        zcx_excel .
     METHODS get_columns_iterator
       RETURNING
-        VALUE(eo_iterator) TYPE REF TO zcl_excel_collection_iterator .
+        VALUE(eo_iterator) TYPE REF TO zcl_excel_collection_iterator
+      RAISING
+        zcx_excel .
     METHODS get_style_cond_iterator
       RETURNING
         VALUE(eo_iterator) TYPE REF TO zcl_excel_collection_iterator .