Possible cause of "copy tampered file error"

Possible cause of "copy tampered file error"

Question:
What is the possible cause of error below?

<Log><TM>063359</TM><MT>Error</MT><DB>Contents and DB</DB>
<Msg>/var/www/html/test.php. copy tampered file error (FILE_ERR_SOURCE).
</Msg></Log>

Answer:
This can be due to the following causes:
- WAA could not read from the tampered file /var/www/html/test.php
- The tampered file /var/www/html/test.php was deleted
- The tampered file /var/www/html/test.php was locked by other processes

More Information:
The user manual has basic explanation of many other error messages.
It will be help to find out root cause of errors.