There is a bug in the OnlyOffice module when you use it in edit mode via a weblink.
Onlyoffice returns a message : 'impossible to save the document'.
The problem is that the variable callbackUrl not have id_rnd.
By adding the following code after line 72 to
$weblinkInfo = $this->data['weblink']['linkInfo'];
it solves the problem of the link without id_rnd, but
as it's not a system weblink the application returns a message 'Invalid link type!'
to the callbackUrl of a json expected by OnlyOffice.
Moreover, when you configure a web link to use onlyOffice in preview mode, it still launches in edit mode
I don't know how this is fixed.
Thanks for your help.
Customer support service by UserEcho