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Maybe you disabled JavaScript.

Yes, javascript is enabled

I check some problems with javascript:

ailed to load resource: the server responded with a status of 403 (Forbidden) /javascript/min/common.js
Failed to load resource: the server responded with a status of 403 (Forbidden) /javascript/min/ajax.js
Failed to load resource: the server responded with a status of 403 (Forbidden) /javascript/min/addLoadEvent.js
Failed to load resource: the server responded with a status of 403 (Forbidden) /javascript/min/xmlhttprequest.js
Failed to load resource: the server responded with a status of 403 (Forbidden) /javascript/min/dynamic_filters.js
2
Uncaught ReferenceError: checkall is not defined view_all_bug_page.php:31

I see permisssions problems in my server!

I'll have a look

I see the problem, my hosting, is disabling to access to folder javascript/.

My hosting, is an ISPCONFIG 3.
In some way it has a virtualhost configured with this folder /javascript.

I don't know if i can disable this javascript/ folder without breaking things in ISPCONFIG.

I adopted another solution, rename folder "javascript" to "js"

And change de source code of mantis.

plugins/MantisGraph/pages/bug_graph_page.php: echo '<link rel="stylesheet" type="text/css" href="', helper_mantis_url( 'javascript/min/jscalendar/calendar-blue.css' ), '">' . "\n";
plugins/MantisGraph/pages/bug_graph_page.php: echo '<link rel="stylesheet" type="text/css" href="', helper_mantis_url( 'javascript/dev/jscalendar/calendar-blue.css' ), '">' . "\n";
core/html_api.php: echo '<script type="text/javascript" src="', helper_mantis_url( 'javascript/min/' . $p_filename ), '"></script>' . "\n";
core/html_api.php: echo '<script type="text/javascript" src="', helper_mantis_url( 'javascript/dev/' . $p_filename ), '"></script>' . "\n";

to this:

plugins/MantisGraph/pages/bug_graph_page.php: echo '<link rel="stylesheet" type="text/css" href="', helper_mantis_url( 'js/min/jscalendar/calendar-blue.css' ), '">' . "\n";
plugins/MantisGraph/pages/bug_graph_page.php: echo '<link rel="stylesheet" type="text/css" href="', helper_mantis_url( 'js/dev/jscalendar/calendar-blue.css' ), '">' . "\n";
core/html_api.php: echo '<script type="text/javascript" src="', helper_mantis_url( 'js/min/' . $p_filename ), '"></script>' . "\n";
core/html_api.php: echo '<script type="text/javascript" src="', helper_mantis_url( 'js/dev/' . $p_filename ), '"></script>' . "\n";

so the bugs and strange things now are working.

Issue solved