Error on Page Updating

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Works well previously, but now, when I edit a page and press "Update" button (inside Tiny Editor), a box come out saying "Error", but no more details. Please help

 
Mnkras replied on at Permalink Reply
Mnkras
did you recently update your site
triac replied on at Permalink Reply
The same happens to me. I just installed Concrete5 and the pre-install test was perfect (no errors, no warnings). The sample site seems to have no problems at all, but as soon as I press the update button after trying to modify some text I get an error window. The caption of the window just reads "Error" and its content is the website itself. The Concrete5 version is the 5.4.1.1
Thanks in advance to anyone could help.