I am trying to download Bitcoin Core, but I keep running into the problem: "Unable to replay blocks. You will need to rebuild the database using reindex chainstate." What is likely the problem?
Delete everything in your folder. Download Bitcoin Core and run it. It has to reindex the entire blockchain - takes some time.
Supporting this suggestion. In the case when Core's databases gave some glitches reindex may turn into lingering-procedure thus the starting from the scratch the building fresh blockchain looks like a well-reasoned decision. To accelerate this IBD I would advocate to put the following entries into bitcoin.conf file : dbcache=1/4 RAM ( i.e. for 8 Gb of RAM
for instance dbcache=2048) and blocksonly=1
(can be deleted/ comment_out after IBD completed).