Check if there is a file called maintenance.flag and if so delete it.

Magento 1.x : maintenance.flag file is in : magento root directory

Magento 2.x : maintenance.flag file is in : var folder

When Magento is performing certain tasks it temporarily creates this file. Magento checks for its existence and if it's there will send users to the page you described.

It's supposed to automatically delete this file when done processing whatever task it was doing, but I've experienced occasions where something went wrong and it failed to delete it.

You can do this thing:

Go to http://localhost/magento/downloader url. Here I am running the magento store on my localhost. Now you can login to magento connect manager and uninstall the extension which you installed previously.

Hope this works !!!!!

Thanks.

Simply delete the maintenance.flag file in root folder and then delete the files of cache folder and session folder inside var/ folder.

If removing the flag shows service temporary unavailable. Go to "http://localhost.com/downloader" and unisntall slider banner,BusinessDecision_Interaktingslider,lightbox2 and anotherone that I dont remember.

I had the same issue but have not found the maintenance.flag file in my Magento root. I simply deleted cache and sessions files and all worked again.

Now in new version magento2 on Generate error Service Temporarily Unavailable.

Remove maintenance.flag

From this path which is changed magento2/var/maintenance.flag.

Also

$ rm maintenance.flag

go to your website via FTP/Cpanel, find maintenance.flag and remove

To fix Service Temporarily Unavailable Magento 2, you should:

• Delete a file called var/.maintenance.flag in Magento root folder
• Remove Magento cache if any: php bin/magento cache:flush

In Magento 2 You have to remove file located in /var/.maintenance.flag - just realized that after some searching, so i shall share.

You need to follow these steps:

1. Go to magento root directory via cPanel/FTP
2. In case of Magento1, you will find maintenance.flag and delete it
3. In case of Magento2, delete var/maintenance.flag

Check the root folder of your Magento installation directory .You will find maintenance.flag file, delete it and refresh the site .it will work fine.

I happen all the time when you install a new plugin. You just have to delete maintenance.flag file in your root directory

If you run into this problem (like I did) and NO maintenance.flag file exists anywhere, it's the Redis cache that's causing the problem; clear it.

I had to clear the Redis cache by contacting my hosting company and let them do it because I don't have access to that cache.

I figured this out using this answer: https://magento.stackexchange.com/a/55814/77803