BSC validator node fails to start with "Missing ancient data file" when using pruned PBSS snapshot - BSC FAQs

BSC validator node fails to start with “Missing ancient data file” when using pruned PBSS snapshot¶

Issue¶

When starting a BSC node (such as a validator) after extracting a pruned PBSS (Path-Based Storage Scheme) snapshot, the process fails with an error indicating a missing ancient data file or an inability to locate the freezer directory.

Solution¶

This issue typically occurs because the node cannot find the ancient block data or because the directory structure of the extracted snapshot does not match Geth’s default expectations.

1. Download All Required Files¶

Choose either the Full Snapshot or the Pruned Snapshot for the required network and supported client version. They are alternative snapshot sets; do not combine the full set with the -pruneancient set. Download and extract every required part of the chosen set.

Use the latest official fetch-snapshot.sh script and verify the checksums. To select a pruned snapshot, use -p with the base snapshot name; do not also append -pruneancient to that name. Extract into the node datadir with -E so the data is placed under <datadir>/geth/chaindata/.

2. Explicitly Specify the Ancient Directory¶

Use the --datadir.ancient flag to point Geth directly to the ancient data location. Note that newer versions of BSC Geth often expect a chain sub-directory within the ancient folder.

Example Startup Configuration:

geth --config ./config.toml \
  --datadir ./node \
  --datadir.ancient ./node/geth/chaindata/ancient/chain \
  --syncmode=full \
  --history.transactions=600000 \
  --history.blocks=600000 \
  --history.logs=600000 \
  --tries-verify-mode=local
# Add your existing network, validator, and other node-specific options.

Note: If your extracted ancient folder does not contain a chain sub-folder (i.e., data files are directly inside ancient/), point the path to .../ancient.

3. Required Parameters for Pruned Snapshots¶

The current official snapshot guide uses --history.blocks for block-history retention, together with the transaction/log history and local verification settings shown above. The old --pruneancient flag is deprecated and is not required to use these snapshots.

600000 is a block count, not a fixed duration; the time covered depends on the block interval. Keep the other options required for your node role and consult the guide for the selected snapshot and client version.

4. Verify Directory Structure¶

Ensure that the path provided to --datadir.ancient contains the actual freezer data files. If the node fails to find them, verify that the extraction process completed without errors and that the files are not located in a different subdirectory.

Reference¶

Official BSC snapshots: download, extraction, and pruned-snapshot startup settings

Applies to: BSC Geth v1.7.2+