PHP：exif_read_data() not defined

• Do you have these DLLs on your system under Php/ext folder?

• Have you restarted Apache after editing the php.ini?

• The php.ini you edited is the one used by system? You can verify this reading <?php phpinfo() ?> output.

• Is there in <?php phpinfo() ?> output some information about the EXIF extension?

If you have exif.so or php_exif.dll enabled under php.ini dynamic extensions, but you still have problem running any function, it is possible that you may need to change order of extensions in php.ini.

In many PHP installation packages the extensions are listed alphabetically. However, exif is dependent on mbstrings to be loaded first. Yet, with alphabetic ordering the exif is listed before mbstrings and it causes the error. Load mbstrings extensions before exif.

Thus, do put exif as the very last extension to load and you should be fine.

http://php.net/manual/en/book.exif.php