Pdf download but not open

I created an application in which a PDF file opens in a web viewer. And this PDF is also downloaded to the phone storage. The downloaded PDF opens in a web browser. But opening a downloaded PDF does not open in Adobe Reader. And here comes the wise error.
The document could not be opened because it is corrupt or damaged.

How can this problem be solved?

Please show us your blocks in order to get help

is mistake in my block?

Hello Mem,
My Block is perfect ?

please help me
how can solve this problem?