Hello,

I had the same error and I'm also using a raspbery pi 3b+ and a HDD. Deleting the file worked for me.
Also, I recommend that you initialize the bitcoin blockchain on a more powerful computer, get 100% on your HDD, and then plug the HDD back into your raspberry pi.
And for cache, raspberry pi 3b+ cannot support the default dbcache present in bitcoincore. I recommend that you put the value dbcache=50 in your bitcoin.conf file.

Regards,

Ghoost