Maybe just needs to be made autoloadable, like its file-contents sibling?

This function was just introduced at commit

7cc233e1e3da297882c006c1f07c628fbd4e94d5

Trigger the error by starting emacs and saying M-x list-packages.

Work around it by (load-library "url-handlers") or equivalent.

--César

You can run the command ‘list-packages’ with M-x l-pac RET

error in process filter: Symbol’s function definition is void: url-insert-buffer-contents [4 times]

Package refresh done

error in process filter: Symbol’s function definition is void: url-insert-buffer-contents [2 times]