Point to Remember concerning the Magento Compiler:
Whenever one installs the 3rd party extension or module and if he/she faces the Fatal error: Uncaught exception regarding the Mage registry key “_singleton/ and so on.. then It would/may point one’s attention towards the Magento compilation state.
“What is being Happening…!”:
If the magento Compilation was enabled by run it in the past and current day, the attempt for the installation of the 3rd party extension(s) made. so, compiler was looking into kind of its repository and/or ‘includes/src’ and the entries for the newly installed extension was not found. So, the system causes the registry error.
For that; one can go to server [where Magento resides] command prompt and follow:
First of all; has to reach to the Magento root directory then,
php -f compiler.php help and can get the below output:
state Show Compilation State
compile Run Compilation Process
clear Disable Compiler include path and Remove compiled files
enable Enable Compiler include path
disable Disable Compiler include path
help This help
The shell commands can be fired with following manner:
php -f compiler.php disable
php -f compiler.php clear
php -f compiler.php compile
Performing compilation process may eliminate such errors But, It is recommended to:
Not compile the Magento while on production server.
Disable the compiler.
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