# Bulk Upload Class ID Issue Fix

## Problem
When trying to upload students via bulk upload, users were getting the error:
```
Row 2: অবৈধ ক্লাস আইডি '1'। এই ক্লাসটি সিস্টেমে নেই।
```

## Root Cause
The CSV templates provided in the system were using class ID '1', but the actual valid class IDs in the database are 6, 7, 8, 9, and 10.

## Solution
1. Updated the CSV templates to use valid class IDs:
   - `bulk_upload/templates/students_template.csv` - Changed Class ID from '1' to '6'
   - `bulk_upload/templates/students_template_updated.csv` - Updated all Class IDs to valid ones (6, 7, 8, 9, 10)

2. Updated the documentation in the upload pages to show valid class IDs:
   - `bulk_upload/students_upload.php` - Updated Class ID example and valid IDs
   - `bulk_upload/students_upload_bengali.php` - Updated Class ID example and valid IDs

## Valid Class IDs
The current valid class IDs in the system are: 6, 7, 8, 9, 10

Users should use one of these IDs in the "Class ID" column of their CSV files, or select a default class from the dropdown during upload.

## How to Avoid This Issue in the Future
1. Always check the valid class IDs in the system before creating templates
2. Run the `check_classes.php` script to verify valid IDs
3. Update templates when class IDs change in the system