You have a couple of choices:
The first (and simplest) is for you to delete the entry in the database. I think there’s a database access module now, which can help you get rid of that entry in the table.
If you are SQL savvy, you can delete the entry yourself by logging into the console as ‘root’ and connecting to the database with “mysql -u root asterisk”. Once in, you can type:
delete from endpoint_global where `key` = ‘legacyXML’;
The tick marks around ‘key’ are important because key is a reserved word in MySQL and MariaDB. Restart the install and wait for the next error (if there is one). Since you uninstalled the endpoint module, you could also the the endpoint_global table altogether and let the install program recreate it.
The second is to submit an issues ticket so that the developers can try to get rid of the problem permanently (by using ‘replace’ instead of ‘insert’ or by deleting the table on a new install).
I tried doing it through SQL and got the following error about syntax. I’m not SQL savvy but tried it anyway as I couldn’t find where to edit it in the GUI.
MariaDB [asterisk]> delete from endpoint_global where key = ‘legacyXML’;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ‘key = ‘legacyXML’’ at line 1