The error The document cannot be opened because it is not a valid PDF file can appear on the tablet when trying to download a PDF from a website. The message appears because file was not downloaded completely. This may be because the file is too large, or if there is an issue between the tablet browser and the website that keeps the file from downloading properly. Follow this procedure to verify whether or not the file downloaded properly.
- On the desktop, tap the Home icon.
- In the upper-right corner of the desktop home screen, tap the Apps & Widgets icon.
- In the Apps & Widgets screen, tap the File transfer icon.
- In the File transfer screen, under the Internal storage, scroll to and tap Download folder.
- In the Download folder, look at the file size of the PDF file you were attempting to view. If that file size does not match the file size of the source file, then the file did not download properly or completely.
NOTE: Typically, when this issue does occur, the file size listed in the Download folder is dramatically less (8-10 bits as opposed to 100-200KB or more).
If you verify that the file did not download properly, try downloading the file again. If it still does not download properly you will need to download the file using a computer, and then transfer the file from the computer to the tablet using either an SD card, a direct USB connection, or by emailing the PDF file to an account accessible by the tablet.