Byzantium Revert (v1.8.21)

Geth 1.8.21 is an emergency hotfix release to postpone the mainnet Constantinople upgrade! The reason is a last minute reentrancy vulnerability dicovered by ChainSecurity.

If you don't feel comfortable with upgrading to Geth 1.8.21, you also have the option to:

• Downgrade to Geth 1.8.19; or
• Continue running Geth 1.8.20 using the --override.constantinople=9999999 flag.

See details here.

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Beside the emergency Constantinople delay, the release also contains some tweaks:

• Return the pending nonce from the transaction pool, not the pending block (#15794).
• Accept application/json-rpc too as the RPC API content type (#18310).
• Sanitize transaction pool config to avoid invalid user settings (#17210).
• Convert ABI names to properly camel-cased names (#16513, #18372).
• Warn the user when the IPC path is too long for the kernel (#18330).
• Support CALLs from the Go APIs against specific blocks (#17942).
• Bubble up internal ABI parsing errors to the caller (#17328).
• Support dumping the CLI configs directly to a file (#18327).
• Switch Keccak implementation to upstream Go (#18390).
• Add CREATE2 support to the callTracer (#18318).
• Bump all builders to Go 1.11.4 (#18314).

And some bugfixes:

• Fix a downloader panic caused by the side chain import rework (#18335).
• Fix an ABI unpacking issue when parsing 2 dimensional slices (#18321, #18364).
• Fix a discovery protocol error when looking up remote peers (#18309).
• Fix puppeth panic when using degenerate genesis configs (#18344).
• Fix compilation regression on PPC64 processors (#18376).
• Fix broken database version tracking (#18429).

For a full rundown of the changes please consult the Geth 1.8.21 release milestone.

Geth binaries and mobile libraries are available on the Geth download page.