cannot copy <filename> cannot read from the source file or disk.

Avast Free Antivirus / Premium Security
1

I have a peculiar failure that occurs when AVAST is running, and does not occur when AVAST is turned off.

It appears to have to do with copying remote files to local volumes mounted in a folder under NTFS… here are the steps to reproduce:

  1. AVAST is running on a Win XP Pro 64 machine.

  2. From the XP 64 machine, map a drive located on another machine to a local drive letter. In my case, the remote machine (in the same Workgroup) is a Win XP Pro 32 bit machine.

  3. ON THE Win XP 32 machine, right-click in a folder of the shared drive and use New → Text Document

  4. Name the file README.TXT (NOTE: USE ALL CAPS, or the problem may not occur, though I have had mixed case files do this)

  5. Edit the file with Notepad and put some characters in so that it has non-zero length

  6. Back on the XP 64 machine, navigate on your mapped drive to locate the README.TXT file.

  7. Use drag and drop or right-click Copy/Paste to transfer the file to a drive mounted in a path on the XP 64 machine.

  8. The copy will fail with a Windows Explorer dialog that says:

Cannot copy README: Cannot read from the source file or disk.

  1. Turn off AVAST, the operation succeeds.
  2. Turn AVAST back on, the operation will fail.

NOTES:

  1. Notice that in the error dialog, the file extension is missing.

  2. Many file copy operations succeed - I have not narrowed down what characteristics of a file make it fail.

  3. Following the steps above, the copy ALWAYS fails with AVAST on, and succeeds with AVAST off.

  4. Copying to a local volume that is NOT mounted in an NTFS folder (a normal drive with a drive letter) succeeds.

  5. To mount a volume in an NTFS folder, use Disk Manager in Computer Management and right click on a drive and choose the options to mount the drive in an empty folder on another drive. It is this kind of target that fails to copy.

2

Based on the description, it seems you’ve spent quite a while on it. It’s a very strange problem, to say the least.

Anyway, we’ve been able to simulate the issue… and hopefully do something about it. A beta version of the upcoming update should be available in very few days, so you are welcome to try it and report the improvements (if any, of course).

3

igor,

Yes - it is a strange problem. It took a while to narrow down the circumstances.

Unfortunately, the impact is large because I regularly do copies from one machine another for backup purposes: my backup volumes are just disk drives mounted in an NTFS folder. Periodically, I’ll dismount a disk, hot swap it out, and take it off site.

When the error occurs, it just makes the whole tree copy fail.

How do I access the beta when it comes out?

Thanks for the response.

4

It is generally released on the forum, you download, upgrade to the beta.
When the beta period finished, the update will upgrade to the final release automatically.

5

Beta 4.7.971 fixed the problem.

Nice job!