A basic command always fails and causes ExifTool itself results in 0 byte

[punkin]

OS: Windows 10 Professional
ExifTool versions: exiftool-12.64, exiftool-12.55, ...

A basic command: exiftool a.jpg

Expected: extract metadatata from a.jpg

Actual:
(1) a.jpg is automatically opened in the Windows default photo app.
(2) exiftool.exe itself becomes zero (0) byte.

If the command goes with at least one option, it will be fine.  For example,

• exiftool -ALLDates a.jpg
• exiftool -Orientation a.jpg

I also tried and tested with exiftool-11.91, the oldest version I had on hand.  But I forget to save a copy.  After the execution, now the file is void because of zero byte.

[StarGeek]

Make an exception for exiftool in your virus checker.  Defender sometimes will tag exiftool as malicious.

I once had a different virus checker (can't remember which one) which would quarantine some of my programs (other than exiftoo) and the result exactly as you describe.  The program would show up as 0 bytes.  I finally figured it out, went into the quarantine section of the antivirus, and was able to restore the programs from there.

[punkin]

Thank you for the trick.  In my case, it is kind of weird.  I use Avast and have Defender disabled.  There is no message reported by Avast and its quarantine or virus section is all clean.  Nothing is shown inside with Avast. 

Before I disabled Avast, I ensured this problem before I went next.  As soon as I disabled Avast, the issue went away.  Then I enabled Avast.  What a surprise! The problem disappears.  This issue is no longer to appear either.  It looks like that turning on and off Avast Protection does a trick!

For the long run, I would prefer your suggestion to make an exception for ExifTool. 

Sorry to report this.  Thanks for taking your time to answer me.  Again, thank you.

[StarGeek]

Sorry to report this.  Thanks for taking your time to answer me.  Again, thank you.

No worries.  It is a weird and obscure problem.  And now that you mentioned Avast, it is quite likely that is what I was using at the time.