URGENT: Autoload error Vendor autoload is not found. Please run 'composer install'..."

[candybmelt262f]

hi all, 
We have a small business and the website it built using Magento. Out of the blue we have this error message "Autoload error, Vendor autoload is not found." 
Now I cannot log into the magento account, or visit the website... THe trouble is the rootfile is not on AW2 EC2... so cannot even give access to my IT consultant to help...

Any one has similar experience please or do we know any good Magento expert who does not mind to help? (Happy to pay and get it fixed...)

[siddiqui208]

Hi, please follow the steps below to help eliminate errors. Thank you!

Step 1: Go to your Magento root directory
cd /var/www/html/magento2
(Please Use your actual Magento path)
Step 2: Check for the vendor folder
ls -l
If the vendor folder is missing, continue with the next step.
Step 3: Install Composer dependencies

Run:
composer install

Download all Magento dependencies.
Generate the missing vendor/autoload.php file.

Step 4: Verify the autoload file
Ensure this file exists:
/vendor/autoload.php

Make sure composer run successfully.

Step 5: Set proper file permissions
After installation:

find var generated vendor pub/static pub/media app/etc -type f -exec chmod g+w {} +
find var generated vendor pub/static pub/media app/etc -type d -exec chmod g+ws {} +
chmod u+x bin/magento

Step 6: Clear and rebuild cache
bin/magento cache:clean
bin/magento cache:flush

Step 7: Run setup upgrade
bin/magento setup:upgrade