Thank you very much for your co-operation.
Please open accelerated-moblie-pages.php in code editor and go to line no 461
you will see the code like this
if( file_exists(realpath(plugin_dir_path(FILE).'../amp/amp.php')) ){
Just rename FILE
constant to __FILE__
So the new code will look like this
if( file_exists(realpath(plugin_dir_path(__FILE__).'../amp/amp.php')) ){
Also same thing in line no 470
if($GLOBALS['pagenow'] === 'plugins.php' && file_exists( realpath(plugin_dir_path(FILE).'../amp/amp.php') ) ){
to like this
if($GLOBALS['pagenow'] === 'plugins.php' && file_exists( realpath(plugin_dir_path(__FILE__).'../amp/amp.php') ) ){
Screenshot for more help https://take.ms/uBPWx
Do let me know if this fixed the issue for you so I can push the update immediately.