diff --git a/app/Abstracts/Import.php b/app/Abstracts/Import.php
index a84907497..4e639ceeb 100644
--- a/app/Abstracts/Import.php
+++ b/app/Abstracts/Import.php
@@ -3,6 +3,7 @@
 namespace App\Abstracts;
 
 use App\Traits\Import as ImportHelper;
+use Illuminate\Support\Arr;
 use Illuminate\Support\Str;
 use Jenssegers\Date\Date;
 use Maatwebsite\Excel\Concerns\Importable;
@@ -15,6 +16,7 @@ use Maatwebsite\Excel\Concerns\WithHeadingRow;
 use Maatwebsite\Excel\Concerns\WithMapping;
 use Maatwebsite\Excel\Concerns\WithValidation;
 use Maatwebsite\Excel\Validators\Failure;
+use Illuminate\Support\Facades\Validator;
 
 abstract class Import implements ToModel, SkipsOnError, SkipsOnFailure, WithBatchInserts, WithChunkReading, WithHeadingRow, WithMapping, WithValidation
 {
@@ -87,4 +89,24 @@ abstract class Import implements ToModel, SkipsOnError, SkipsOnFailure, WithBatc
     {
         flash($e->getMessage())->error()->important();
     }
+
+    public function isNotValid($row)
+    {
+        return Validator::make($row, $this->rules())->fails();
+    }
+
+    public function isEmpty($row, $fields)
+    {
+        $fields = Arr::wrap($fields);
+
+        foreach ($fields as $field) {
+            if (!empty($row[$field])) {
+                continue;
+            }
+
+            return true;
+        }
+
+        return false;
+    }
 }
diff --git a/app/Imports/Purchases/Sheets/BillHistories.php b/app/Imports/Purchases/Sheets/BillHistories.php
index b534ef5cf..c42bc7b9f 100644
--- a/app/Imports/Purchases/Sheets/BillHistories.php
+++ b/app/Imports/Purchases/Sheets/BillHistories.php
@@ -11,7 +11,7 @@ class BillHistories extends Import
 {
     public function model(array $row)
     {
-        // @todo remove after 3.2 release
+        // @todo remove after laravel-excel 3.2 release
         if ($row['bill_number'] == $this->empty_field) {
             return null;
         }
@@ -21,9 +21,13 @@ class BillHistories extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'bill_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['bill_id'] = Bill::number($row['bill_number'])->pluck('id')->first();
+        $row['bill_id'] = (int) Bill::number($row['bill_number'])->pluck('id')->first();
 
         $row['notify'] = (int) $row['notify'];
 
diff --git a/app/Imports/Purchases/Sheets/BillItemTaxes.php b/app/Imports/Purchases/Sheets/BillItemTaxes.php
index 817ccb955..21b0062ba 100644
--- a/app/Imports/Purchases/Sheets/BillItemTaxes.php
+++ b/app/Imports/Purchases/Sheets/BillItemTaxes.php
@@ -13,7 +13,7 @@ class BillItemTaxes extends Import
 {
     public function model(array $row)
     {
-        // @todo remove after 3.2 release
+        // @todo remove after laravel-excel 3.2 release
         if ($row['bill_number'] == $this->empty_field) {
             return null;
         }
@@ -23,9 +23,13 @@ class BillItemTaxes extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'bill_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['bill_id'] = Bill::number($row['bill_number'])->pluck('id')->first();
+        $row['bill_id'] = (int) Bill::number($row['bill_number'])->pluck('id')->first();
 
         if (empty($row['invoice_item_id']) && !empty($row['item_name'])) {
             $item_id = Item::name($row['item_name'])->pluck('id')->first();
diff --git a/app/Imports/Purchases/Sheets/BillItems.php b/app/Imports/Purchases/Sheets/BillItems.php
index 5e1f254e9..c3ddc5c0d 100644
--- a/app/Imports/Purchases/Sheets/BillItems.php
+++ b/app/Imports/Purchases/Sheets/BillItems.php
@@ -16,9 +16,13 @@ class BillItems extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'bill_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['bill_id'] = Bill::number($row['bill_number'])->pluck('id')->first();
+        $row['bill_id'] = (int) Bill::number($row['bill_number'])->pluck('id')->first();
 
         if (empty($row['item_id']) && !empty($row['item_name'])) {
             $row['item_id'] = $this->getItemIdFromName($row);
diff --git a/app/Imports/Purchases/Sheets/BillTotals.php b/app/Imports/Purchases/Sheets/BillTotals.php
index b425d9f26..6dfbb591c 100644
--- a/app/Imports/Purchases/Sheets/BillTotals.php
+++ b/app/Imports/Purchases/Sheets/BillTotals.php
@@ -16,9 +16,13 @@ class BillTotals extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'bill_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['bill_id'] = Bill::number($row['bill_number'])->pluck('id')->first();
+        $row['bill_id'] = (int) Bill::number($row['bill_number'])->pluck('id')->first();
 
         return $row;
     }
diff --git a/app/Imports/Purchases/Sheets/BillTransactions.php b/app/Imports/Purchases/Sheets/BillTransactions.php
index 6f6952687..b5e08c265 100644
--- a/app/Imports/Purchases/Sheets/BillTransactions.php
+++ b/app/Imports/Purchases/Sheets/BillTransactions.php
@@ -15,6 +15,10 @@ class BillTransactions extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'bill_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
         $row['type'] = 'expense';
diff --git a/app/Imports/Purchases/Sheets/Bills.php b/app/Imports/Purchases/Sheets/Bills.php
index 768b1fa97..38202527e 100644
--- a/app/Imports/Purchases/Sheets/Bills.php
+++ b/app/Imports/Purchases/Sheets/Bills.php
@@ -15,6 +15,10 @@ class Bills extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'bill_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
         $row['category_id'] = $this->getCategoryId($row, 'expense');
diff --git a/app/Imports/Sales/Sheets/InvoiceHistories.php b/app/Imports/Sales/Sheets/InvoiceHistories.php
index a40afcdd2..aa5422647 100644
--- a/app/Imports/Sales/Sheets/InvoiceHistories.php
+++ b/app/Imports/Sales/Sheets/InvoiceHistories.php
@@ -11,7 +11,7 @@ class InvoiceHistories extends Import
 {
     public function model(array $row)
     {
-        // @todo remove after 3.2 release
+        // @todo remove after laravel-excel 3.2 release
         if ($row['invoice_number'] == $this->empty_field) {
             return null;
         }
@@ -21,9 +21,13 @@ class InvoiceHistories extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'invoice_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['invoice_id'] = Invoice::number($row['invoice_number'])->pluck('id')->first();
+        $row['invoice_id'] = (int) Invoice::number($row['invoice_number'])->pluck('id')->first();
 
         $row['notify'] = (int) $row['notify'];
 
diff --git a/app/Imports/Sales/Sheets/InvoiceItemTaxes.php b/app/Imports/Sales/Sheets/InvoiceItemTaxes.php
index 68cfaf91a..79f77d169 100644
--- a/app/Imports/Sales/Sheets/InvoiceItemTaxes.php
+++ b/app/Imports/Sales/Sheets/InvoiceItemTaxes.php
@@ -13,7 +13,7 @@ class InvoiceItemTaxes extends Import
 {
     public function model(array $row)
     {
-        // @todo remove after 3.2 release
+        // @todo remove after laravel-excel 3.2 release
         if ($row['invoice_number'] == $this->empty_field) {
             return null;
         }
@@ -23,9 +23,13 @@ class InvoiceItemTaxes extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'invoice_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['invoice_id'] = Invoice::number($row['invoice_number'])->pluck('id')->first();
+        $row['invoice_id'] = (int) Invoice::number($row['invoice_number'])->pluck('id')->first();
 
         if (empty($row['invoice_item_id']) && !empty($row['item_name'])) {
             $item_id = Item::name($row['item_name'])->pluck('id')->first();
diff --git a/app/Imports/Sales/Sheets/InvoiceItems.php b/app/Imports/Sales/Sheets/InvoiceItems.php
index 0222bf547..b0162eab1 100644
--- a/app/Imports/Sales/Sheets/InvoiceItems.php
+++ b/app/Imports/Sales/Sheets/InvoiceItems.php
@@ -16,9 +16,13 @@ class InvoiceItems extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'invoice_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['invoice_id'] = Invoice::number($row['invoice_number'])->pluck('id')->first();
+        $row['invoice_id'] = (int) Invoice::number($row['invoice_number'])->pluck('id')->first();
 
         if (empty($row['item_id']) && !empty($row['item_name'])) {
             $row['item_id'] = $this->getItemIdFromName($row);
diff --git a/app/Imports/Sales/Sheets/InvoiceTotals.php b/app/Imports/Sales/Sheets/InvoiceTotals.php
index 3d8606497..b3d1d5424 100644
--- a/app/Imports/Sales/Sheets/InvoiceTotals.php
+++ b/app/Imports/Sales/Sheets/InvoiceTotals.php
@@ -16,9 +16,13 @@ class InvoiceTotals extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'invoice_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
-        $row['invoice_id'] = Invoice::number($row['invoice_number'])->pluck('id')->first();
+        $row['invoice_id'] = (int) Invoice::number($row['invoice_number'])->pluck('id')->first();
 
         return $row;
     }
diff --git a/app/Imports/Sales/Sheets/InvoiceTransactions.php b/app/Imports/Sales/Sheets/InvoiceTransactions.php
index 1b4ec7e9f..2c5e94b11 100644
--- a/app/Imports/Sales/Sheets/InvoiceTransactions.php
+++ b/app/Imports/Sales/Sheets/InvoiceTransactions.php
@@ -15,6 +15,10 @@ class InvoiceTransactions extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'invoice_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
         $row['type'] = 'income';
diff --git a/app/Imports/Sales/Sheets/Invoices.php b/app/Imports/Sales/Sheets/Invoices.php
index d13377113..43b986dfd 100644
--- a/app/Imports/Sales/Sheets/Invoices.php
+++ b/app/Imports/Sales/Sheets/Invoices.php
@@ -15,6 +15,10 @@ class Invoices extends Import
 
     public function map($row): array
     {
+        if ($this->isEmpty($row, 'invoice_number')) {
+            return [];
+        }
+
         $row = parent::map($row);
 
         $row['category_id'] = $this->getCategoryId($row, 'income');