Dear Iuri,
this problem occurred in a file local to your site [1], that you use in file-storage/view. The old name "ad_html_text_convertable_p" contained a typo [2] and was replaced by "ad_html_text_convertible_p" in the (unreleased) oacs-5-10 branch. To improve backward compatibility, i've added the function with the old name and marked it as deprecated [3].
[1] /var/www/iurix//templates/file-storage-default
[2] https://english.stackexchange.com/questions/300821/why-convertible-and-not-convertable
[3] http://fisheye.openacs.org/changelog/OpenACS?cs=oacs-5-10%3Agustafn%3A20190316180600
