cannot convert to CIDv0 with any multibase other than the im

Error message

cannot convert to CIDv0 with any multibase other than the implicit base58btc

What it means

When converting a CID to version 0, only the implicit base58btc multibase is valid. CIDv0 predates multibase, so requesting v0 with any other explicit --multibase (e.g. base32) is rejected at option-processing time.

Source

Thrown at core/commands/cid.go:98

			var codec mc.Code
			err := codec.Set(codecStr)
			if err != nil {
				return err
			}
			opts.newCodec = uint64(codec)
		} // otherwise, leave it as 0 (not a valid IPLD codec)

		switch verStr {
		case "":
			if baseStr != "" {
				opts.verConv = toCidV1
			}
		case "0":
			if opts.newCodec != 0 && opts.newCodec != cid.DagProtobuf {
				return errors.New("cannot convert to CIDv0 with any codec other than dag-pb")
			}
			if baseStr != "" && baseStr != "base58btc" {
				return errors.New("cannot convert to CIDv0 with any multibase other than the implicit base58btc")
			}
			opts.verConv = toCidV0
		case "1":
			opts.verConv = toCidV1
		default:
			return fmt.Errorf("invalid cid version: %q", verStr)
		}

		if baseStr != "" {
			encoder, err := mbase.EncoderByName(baseStr)
			if err != nil {
				return err
			}
			opts.newBase = encoder.Encoding()
		} else {
			opts.newBase = mbase.Encoding(-1)
		}

View on GitHub (pinned to 329838acdf)

Solutions

Omit --multibase (or set it to base58btc) when using --cid-ver=0
Use --cid-ver=1 together with --multibase=base32 for base32 output
Post-encode the v0 CID string yourself with a different multibase after conversion

Example fix

// before
ipfs cid format --cid-ver=0 --multibase=base32 <cid>
// after
ipfs cid format --cid-ver=1 --multibase=base32 <cid>

Defensive patterns

Strategy: validation

Validate before calling

if ver == 0 && base != "" && base != "base58btc" {
    return fmt.Errorf("multibase %s incompatible with CIDv0", base)
}

Try / catch

if err != nil && strings.Contains(err.Error(), "multibase other than base58btc") {
    // retry with --cid-ver=1
}

Prevention

Omit --multibase for v0 conversions
Use base58btc by convention for v0 CIDs
Switch to v1+base32 when case-insensitive output is needed

When it happens

Trigger: Running `ipfs cid format --cid-ver=0 --multibase=base32 <cid>` (or any base other than base58btc, or an empty codec plus non-base58btc base) via CLI or the underlying option map.

Common situations: Wanting lowercase/base32 output but keeping v0; mixing flags from a v1-conversion invocation; scripts templating --multibase for all conversions.

Related errors

AI-assisted analysis of ipfs/kubo@329838acdf (2026-09-03). Data as JSON: /api/errors/9d71c199b400eba9. Report an issue: GitHub.