The most likely reason for this error may be one of the 3-rd party system plugins you installed.
Here are the troubleshooting steps,
1. Go to "Extensions => Plugins" from your Joomla! administrator panel.
2. This will bring you to the "Plugins" screen. Click the "Search Tools" button.
3. You will see the four filters appear. Click inside the "Select Type" filter.
4. You will see a dropdown list of the types of plugins. Click "system".
5. Disable filtered system plugins one by one by clicking on the box next to the name of the plugin and check if the error disappeared.
6. Keep disabling your 3-rd party system plugins until you find the one that causes the "Call to undefined method ..." error.
If you are able to locate the conflicting plugin, report the plugin author about this.
In case the issue remains, please send us your Joomla! admin and FTP access details here
allvideoshare.mrvinoth.com/#contact-us
to further investigate the issue.