Many users have reported this issue on various Joomla forums that they are not abe to save module configuration pages after making some edits. This is mainly happening with module and plugin parameter pages too.

After checking and digging the issue, we found out the fix for it.

Here is

Open the admin template ISIS and edit index.php file.

Where you find...
Code:
// Add JavaScript Frameworks
JHtml::_('bootstrap.framework');

Change to...
Code:
// Add JavaScript Frameworks
JHtml::_('bootstrap.framework');
JHtml::_('behavior.framework', true);

Best Joomla Hosting Recommendation

ASPHostPortal.com provides our customers with Plesk Panel, one of the most popular and stable control panels for Windows hosting, as free. You could also see the latest .NET framework, a crazy amount of functionality as well as Large disk space, bandwidth, MSSQL databases and more. All those give people the convenience to build up a powerful site in Windows server. We offers Joomla hosting starts from $5/month only. We also guarantees 30 days money back and guarantee 99.9% uptime. If you need a reliable affordable Joomla Hosting, we should be your best choice.