Hi @ankitdse,
Let’s first check the server settings to make sure you have everything up to date. Reach out to your hosting provider and confirm they have the www.ads-software.com Requirements settings in place:
MySQL v5.6 (or higher)
PHP 7.2 (or higher)
Memory limit: 250MB (or higher)
Upload limit: 50MB (or higher)
Post limit: 50MB (or higher)
/wp-content directory has sufficient permissions (i.e. 755)
With those in place, everything should work smoothly for you. If the issue still shows up, let’s check to see if there is a plugin conflict happening. Temporarily deactivate all plugins, then reactivate NextGEN Gallery only. Does the issue still appear? If so, temporarily switch to a WordPress default theme (this deactivation is only intended to quickly check to see if the issue goes away or is still present). If by deactivating the other plugins the issue does go away, reactivate each of the other plugins one at a time to locate the culprit. Keep me posted on your results ??
Mihai