TUTO chapitre1: find and resolve errors in magento

many developers of magento don't know how explain their errors or find the source of bugs
for that i will writing some solutions
ok the first way you must learning the report of error or bug , if you working in production mode you should go to follder contain the file , by default magento start with production mode ,the sign of error showing in browser , you have like this message

'There has been an error processing your request
Exception printing is disabled by default for security reasons.
Error log record number: 1243095821280'

it s normal because when the site in production mode you don't want the people or client or hakers see the path of files or important information like login name or content of sensitive of xml
ok for viewing of errors you must go to this path in root folder of your site go to '\var\report' , you must see the file with name '1243095821280' in our example (see the messge error in top)
open the file and understand .
all this explain in the production mode but i think you are developer and you must work inside of develop mode
for changing to development mode you have in root .htaccess. open the file and in the first ligne add
SetEnv MAGE_IS_DEVELOPER_MODE "true"
or in root inside index.php in ligne 66
if (isset($_SERVER['MAGE_IS_DEVELOPER_MODE'])) {
Mage::setIsDeveloperMode(true);
}
after that add
Mage::setIsDeveloperMode(true);
and uncomment
#ini_set('display_errors', 1);

(i know inside '\var\log' you must find all exception and errors system but in is not praticle in real time)

(another truc in your root of site , you have a folder with name errors inside this folder you must find local.xml.sample rename to local.xml for set to "print" to show exception on screen you can inside this file add "email" to send exception on specified email)

ok i see you in futur chapitre for continue