Google Search 1.1.0 was rewritten from scratch. It is not compatible with previous addon versions and XF below 2.1! There is no way to upgrade existing addon!
Remove installed Google Search addon from you forum. After this install this version as a new addon!
Improved addon stability
All previously reported bugs should disappear now
Removed google search box from combined forum + google search results page
Custom icon and description for options group in ACP
XF 2.1 and PHP 7+ are required now to install the addon
Fixed a "implode(): Argument must be an array" error
Fixed a bug that redirects to "Google Search" tab when trying to find content of a user who has no content