# Ledger and Index canister compatibility

**URL:** <https://forum.dfinity.org/t/ledger-and-index-canister-compatibility/51454>\
**Category:** Developers\
**Created:** [June 24, 2025, 3:27pm UTC](https://forum.dfinity.org/t/ledger-and-index-canister-compatibility/51454 "2025-06-24T15:27:54Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ckPaul](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@ckPaul](https://forum.dfinity.org/u/ckPaul)\
**Post date:** [June 24, 2025, 3:27pm UTC](https://forum.dfinity.org/t/ledger-and-index-canister-compatibility/51454/1 "2025-06-24T15:27:54Z")

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Hi guys, I need to understand why, when creating an index canister with hash `79075dbdd331a7911b93006be9e174aa9725108c4c79b58d7fbed8ed69d51f65`, I’m only able to retrieve transactions for certain tokens.

For example, I can get the transactions for a token using this WASM: `b60487873e58beda2fe7a02cfdf3c741bc48a30d3485aeec8a69a991d7807d4b`, but I’m unable to retrieve transactions for this other WASM (bob ledger): `25071c2c55ad4571293e00d8e277f442aec7aed88109743ac52df3125209ff45`.

Is there a list of compatible WASMs for each index canister WASM?

Thank You!

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**Author:** ![communitydev](https://avatars.discourse-cdn.com/v4/letter/c/c67d28/32.png) [@communitydev](https://forum.dfinity.org/u/communitydev)\
**Post date:** [June 24, 2025, 6:51pm UTC](https://forum.dfinity.org/t/ledger-and-index-canister-compatibility/51454/2 "2025-06-24T18:51:58Z")

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> [@ckPaul](#):
>
> Is there a list of compatible WASMs for each index canister WASM?

For project-specific canisters, it’s often best to reach out to the developers or the support community to get the officially supported list of WASMs for a particular index canister.

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**Author:** ![mathiasb](https://avatars.discourse-cdn.com/v4/letter/m/f475e1/32.png) [@mathiasb](https://forum.dfinity.org/u/mathiasb)\
**Post date:** [June 24, 2025, 9:25pm UTC](https://forum.dfinity.org/t/ledger-and-index-canister-compatibility/51454/3 "2025-06-24T21:25:04Z")

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Hi @ckPaul,  
Currently, I cannot explain why this wouldn’t work. The index canister you are using, with module hash `79075dbdd331a7911b93006be9e174aa9725108c4c79b58d7fbed8ed69d51f65`, corresponds to the gunzipped version of the [ic-icrc1-index-ng.wasm.gz](https://download.dfinity.systems/ic/a62848817cec7ae50618a87a526c85d020283fd9/canisters/ic-icrc1-index-ng.wasm.gz) canister from commit [a62848817cec7ae50618a87a526c85d020283fd9](https://github.com/dfinity/ic/commit/a62848817cec7ae50618a87a526c85d020283fd9) from November 7, 2024.

The ledger corresponding to module hash `b60487873e58beda2fe7a02cfdf3c741bc48a30d3485aeec8a69a991d7807d4b` corresponds to [ic-icrc1-ledger.wasm.gz](https://download.dfinity.systems/ic/f58b13bc425784cd399070028ff8b3f3dca8c869/canisters/ic-icrc1-ledger.wasm.gz) from commit [f58b13bc425784cd399070028ff8b3f3dca8c869](https://github.com/dfinity/ic/commit/f58b13bc425784cd399070028ff8b3f3dca8c869) from March 2024.

The WASM running on [the bob ledger](https://dashboard.internetcomputer.org/canister/7pail-xaaaa-aaaas-aabmq-cai), `25071c2c55ad4571293e00d8e277f442aec7aed88109743ac52df3125209ff45`, is [ic-icrc1-ledger.wasm.gz](https://download.dfinity.systems/ic/2190613d3b5bcd9b74c382b22d151580b8ac271a/canisters/ic-icrc1-ledger.wasm.gz) from commit [2190613d3b5bcd9b74c382b22d151580b8ac271a](https://github.com/dfinity/ic/commit/2190613d3b5bcd9b74c382b22d151580b8ac271a), from November 28, 2024.

If anything, I would have expected that the index from November 7, 2024, would be compatible with the ledger from November 28, 2024.

In general, I would recommend running an index from the same revision/release as the ledger whose blocks and transactions it is indexing. Keeping the two in sync should be relatively simple if you’re the controller of both, but anyone can spin up an index canister and point it at any ledger, in which case keeping the two in sync wrt. versions gets more complicated. We typically test index-ledger compatibility for adjacent release versions, but not for other canister version pairs.

Regarding the issues in this specific case, does the `https://<index_canister_id>.raw.icp0.io/logs` endpoint offer any further hints about what the problem may be?