I respond to myself but it could help anyone else. Now it works. I modified the about-to-finish event, setting the pipeline to ready, once the uri was set, I change the pipeline state to PLAY again void about_to_finish_cb (GstElement * element, gpointer * uri) { gst_element_set_state (play, GST_STATE_READY); gchar* uri2 = (gchar*)uri; g_object_set (G_OBJECT (element), "uri",uri2, NULL); gst_element_set_state (play, GST_STATE_PLAYING); } Any suggestion are welcome, I don't know if I am doing the right thing. According to some examples change the pipeline state it woudln't necessary, but it didn't work for me. Thanks, Rossana <div class="gmail_quote">2012/1/5 Rossana Guerra <<a href="mailto:guerra.rossana@gmail.com">guerra.rossana@gmail.com</a>> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> The code is very simple, a playbin2, with an uri, and the next uri is set in the about-to-finish signal. void about_to_finish_cb (GstElement * element, gpointer * uri) { gchar* uri2 = (gchar*)uri; g_object_set (G_OBJECT (element), "uri",uri2, NULL); } I tested it by hardcoding also: g_object_set (G_OBJECT (element), "uri","file:///home/videos/video1.avi", NULL); It didn't work either. Here is the code where I do the callback in the main, the whole code is very straight forward, so I think the problem is how I call the about-to-finish event. char uri_next[] = "file:///home/videos/video11.avi"; g_signal_connect (play, "about-to-finish", G_CALLBACK (about_to_finish_cb),uri_next); gst_element_set_state (play, GST_STATE_PLAYING); The error appears in the about_to_finish_cb function, when I try to set the new uri: GLib-GObject-CRITICAL **: g_object_set: assertion `G_IS_OBJECT (object)' failed I checked the mailing list but none of the examples suits mine. Thank you. Rossana </blockquote></div>