alm06130

Found solution, don’t understand yet!
In widget class constructor, replaced:

$this->WP_Widget(false, $name = __('Widget title','my_text_domain'));

by

$this->WP_Widget(false, __('Widget title','my_text_domain'));

Then translate works well now.
If some one can explain…

There are many raisons to have error 500: I happened to have such an error due to bad transfert mode of my FTP client for mo files.
Such files are to be transfered as binaries, my client was wrongly setup on ASCII tranfert instead of automatic.
Re-transfering files in binary mode fixed the case.
Hope this can help you…

First things to do, check characters encoding in each of:
– displayed pages
– db tables
Try to discover whether the problem comes from:
– post
– storing
– retrieving
– displaying