Internal server error when uploading pdf using php

I am uploading 6 pdf files using PHP form but I am getting

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

When I am uploading only one pdf it will uploaded successfully.

My each pdf size is approx 10-15 mb.

can any one please tell me what may cause issue.

I have already set max_execution_time = 111111111111111111;

max_input_time = 11111111111;

memory_limit = 开发者_StackOverflow中文版128M;

max_upload_size =200M;

Can any one please help me to resolve this problem?

this is my form :

Thanks in advance.

And how is your webserver configured for timeouts, max request size, max post size etc?

Didn't you forget to use MAX_FILE_SIZE hidden attribute for POST request?

<input type="hidden" name="MAX_FILE_SIZE" value="20000000">

Note that it must precede the file input field. It is in bytes, so this will limit the upload to 20MB. See PHP documentation for details.