# FuelError: The transaction reverted with an unknown reason: 123

**URL:** <https://forum.fuel.network/t/fuelerror-the-transaction-reverted-with-an-unknown-reason-123/5638>\
**Category:** TypeScript SDK\
**Tags:** testnet, feedback\
**Created:** [June 8, 2024, 3:55pm UTC](https://forum.fuel.network/t/fuelerror-the-transaction-reverted-with-an-unknown-reason-123/5638 "2024-06-08T15:55:33Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![theAusicist](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.fuel.network/theausicist/32/1987_2.png) [@theAusicist](https://forum.fuel.network/u/theAusicist)\
**Post date:** [June 8, 2024, 3:55pm UTC](https://forum.fuel.network/t/fuelerror-the-transaction-reverted-with-an-unknown-reason-123/5638/1 "2024-06-08T15:55:33Z")

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Running into this error when trying to query a read-only function from a contract deployed on Testnet. It works absolutely fine on a local node on the same version as the testnet (v0.28.0) but fails in the wild. The error message is also nonconclusive.

The call is essentially a getter from storage, and I can GUARANTEE there are no reverts in the getter function. It’s a simple storage read with graceful handles for the unwrap() case.

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**Author:** ![danielbate](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.fuel.network/danielbate/32/1617_2.png) [@danielbate](https://forum.fuel.network/u/danielbate)\
**Post date:** [June 9, 2024, 8:30am UTC](https://forum.fuel.network/t/fuelerror-the-transaction-reverted-with-an-unknown-reason-123/5638/2 "2024-06-09T08:30:49Z")

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Hi @theAusicist, sorry you’ve been having issues. Could you share the contract that you are having a problem with? So this is thrown by sway due to a [mismatched selector](https://github.com/FuelLabs/sway/blob/76a6cd34a9b6c197926773afa53b7657cc08576d/sway-core/src/asm_generation/fuel/compiler_constants.rs#L40), so I’d expect a version mismatch with an inter contract call? But again if you share the contract I can take a look.

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**Author:** ![theAusicist](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.fuel.network/theausicist/32/1987_2.png) [@theAusicist](https://forum.fuel.network/u/theAusicist)\
**Post date:** [June 9, 2024, 9:04am UTC](https://forum.fuel.network/t/fuelerror-the-transaction-reverted-with-an-unknown-reason-123/5638/3 "2024-06-09T09:04:14Z")

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@danielbate you are correct that this is due to a mismatched selector. I had used an incorrect contract id for the contract call which is why I had this error. Thanks!

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**Author:** ![system](https://us1.discourse-cdn.com/flex022/uploads/fuel/original/2X/5/57d5a345cc15a64b636e0d56e042857f8a0e80b1.png) [@system](https://forum.fuel.network/u/system)\
**Post date:** [June 30, 2024, 5:05am UTC](https://forum.fuel.network/t/fuelerror-the-transaction-reverted-with-an-unknown-reason-123/5638/4 "2024-06-30T05:05:07Z")

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