Idemix MSP “Version not recognized [4]” error on Fabric v3.0.0 with Fabric CA v1.5

[smahanti-dev]

Description

Bug Report: "Version not recognized [4]" Error with Idemix on Fabric v3.0.0

Description

I am encountering a Version not recognized [4] error when attempting to use an Idemix organization on Hyperledger Fabric v3.0.0, in conjunction with Fabric CA v1.5.13.

Error Details

When I try to join a new channel using osnadmin channel join, the orderer returns the following error:

Status: 400
{
  "error": "invalid join block: initializing channelconfig failed: could not create channel Application sub-group config: creating the MSP manager failed: Invalid *IdemixNewOpts. Version not recognized [4]"
}

Environment

• Hyperledger Fabric: v3.0.0 (orderer and peer images)
• Fabric CA: v1.5.13
• Idemix curve configuration in fabric-ca-server-config.yaml:

idemix:
  curve: amcl.Fp256bn
  rhpoolsize: 1000
  nonceexpiration: 15s
  noncesweepinterval: 15m

• The organization in question is defined in configtx.yaml with msptype: idemix.

Observed Behavior

• Fabric CA is generating IssuerPublicKey and IssuerRevocationPublicKey under the standard Idemix MSP directories (e.g., in msp/).
• Despite configuring amcl.Fp256bn, the orderer sees a key version of 4 and refuses to parse it, citing Version not recognized [4].
• This suggests that the Idemix MSP code in the Fabric orderer (which only accepts versions ≤ 3) is incompatible with the newly generated IPK.

Expected Behavior

• The combination of Fabric v3.0.0 and Fabric CA v1.5.x with amcl.Fp256bn should generate an IPK version that is recognized by the Fabric MSP (i.e., version ≤ 3).
• The osnadmin channel join command should succeed in parsing the Idemix MSP without triggering "Version not recognized [4]".

Question

• Is there a known scenario in Fabric CA or IBM/Idemix that might inadvertently produce a "version 4" IPK, despite amcl.Fp256bn being set?
• Should Fabric v3.0.0’s MSP accept version 4 if Fabric CA is at v1.5? Or is this a bug in one of the code paths?

Any guidance on resolving this issue would be appreciated. Thanks!

Steps to reproduce

• Start a Fabric CA (v1.5) with the idemix: stanza set to amcl.Fp256bn.
• Enroll an Idemix org admin, generating IssuerPublicKey and IssuerRevocationPublicKey.
• Create a configtx that references this org with msptype: idemix.
• Start an orderer (Fabric 3.0) and run osnadmin channel join --channelID <...> --config-block <...> referencing the new organization in the config block.
• Observe the “Version not recognized [4]” error from the orderer logs or the API response.