Log keeps displaying the same error message at a rate of ~5 per second
Exclude from Spotlight

Others reporting this problem suggest external storage may be the cause; a USB stick, network drive, or NAS.

If you have any external storage connected to your Mac, try adding it to the Spotlight Privacy list:


System Preferences > Spotlight > Privacy > + Button


mdworker is a helper process for Spotlight on OS X.

Sources

Mdworker : (Warning) Import : Bad path: wrote:


  The problem is MacOS/Spotlight indexing cannot handle partition in NTFS/FAT32 format, which is windows stuff.


mdworker: (warning) import bad path continuously.  What does it mean? wrote:


  This happened to me too with a fat partition that I have mounted which I share with my other OSs.


Stephen Foskett shared his experience with this bug in Mac OS X Bug: ExFAT Hangs Spotlight and Time Machine:


  I’ve had terrible issues with Mac OS X never completing Spotlight indexing and Time Machine backups. I was pulling out my hair until I decided to check the console log. That’s when I saw this: Thousands of mdworker errors, with a dozen appearing every second.