DOC-2103: Remove dev network and update local development guidance

[bgravenorst]

Do not merge this until confirmed in the Besu release. Post 26.8.0.

Description

Besu removed --network=dev in besu-eth/besu#10836.
The flag isn't merely deprecated: Besu logs a framed warning and then aborts, so every
--network=dev example in the docs was a command that fails at startup. The dev network relied on
ethash.fixeddifficulty and proof of work mining, which was removed earlier, so it can no longer
produce blocks. The same PR also deleted the dev profile, which these docs never listed.

Reference (options.md)

• Removed the dev row from the --network table.
• Added a "Removed networks" warning mirroring the CLI output, pointing to Ephemery and Kurtosis.
• Corrected the ETC/Mordor note: support was removed in besu#9671, not deprecated.
• Dropped the --network=dev exceptions from --bootnodes and --sync-mode, which makes the
  SNAP default unconditional for all remaining named networks.

Examples that no longer start

• Public metrics.md uses --network=ephemery, with a note that Ephemery needs a consensus client.
• Private opentelemetry.md and splunk.md use --genesis-file instead, since readers of
  private-networks pages already run their own network, with links to the Developer Quickstart.
• Removed the "run a node for testing" commands from both Docker pages and private start-node.md.
  Their premise was a single command that produces blocks, and no single command replaces that. The
  security :::caution from start-node.md is kept, relocated under "Run a node on a private
  network".

Replacement guidance for local development

Removing those sections would otherwise leave readers without an answer for how to run a node
locally, so the supported alternatives are documented instead:

• Public start-node.md gains a "Run a node for local development" section covering Ephemery
  (with a consensus client), Kurtosis, and defining your own genesis file for a private network.
  Public networks previously had no local-development guidance anywhere.
• Both Docker pages keep the Run a node for testing heading, now as a short signpost to the
  relevant page. Keeping the original wording preserves the #run-a-node-for-testing anchor that
  external links and search results point at.
• Private start-node.md points readers without a network to the Developer Quickstart or the QBFT
  tutorial.

Other updates

• Removed the dev-mode genesis paragraphs from both start-node.md pages.
• Reframed "Development mode" in accounts-for-testing.md as "Predefined test accounts". The
  accounts still ship in dev.json and remain valid as a template for your own genesis file.

Related issue(s)

Fixes #2103

Preview

• https://besu-docs-git-fork-bgravenorst-doc-2103-hyperledger.vercel.app/public-networks/reference/options#network
• https://besu-docs-git-fork-bgravenorst-doc-2103-hyperledger.vercel.app/public-networks/get-started/start-node#run-a-node-for-local-development
• https://besu-docs-git-fork-bgravenorst-doc-2103-hyperledger.vercel.app/public-networks/get-started/install/run-docker-image#run-a-node-for-testing
• https://besu-docs-git-fork-bgravenorst-doc-2103-hyperledger.vercel.app/private-networks/get-started/start-node

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Project	Deployment	Actions	Updated (UTC)
besu-docs	Ready	Preview	Aug 19, 2026 10:59pm

[alexandratran]

lgtm