"Warning: Cannot modify header information" ... "headers already sent" notices after activation

[herculeeza]

Got this notification after activation:
"The plugin generated 2 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin."

And some random text appears at the top of the dashboard: "Warning: Cannot modify header information - headers already sent by (output started at /homepages///htdocs/clickandbuilds/Test/wp-content/plugins/IPFS-Bridge-master/function.php:34) in /homepages///htdocs/clickandbuilds/Test/wp-admin/includes/misc.php on line 1144" (also for /option.php, line 919 and 920)