You may receive “Failed To Find Flength File” error during file upload using uber uploader. The main cause of this problem is due to apache mod_security enabled on your host. Apache mod_security may prevent writing flength file duing file upload. This will cause uploder to determine file length for percentage calculation and uploader produce file length error.
Solution: This problem can be easily solve by turn off mod_security through .htaccess . We need to turn off mod_security for uploader directory. To solve this problem, create .htaccess file with the following line and upload file to the directory where uploader files reside.
# Turn off mod_security filtering.
# The below probably isn’t needed,
# but better safe than sorry.