How can I fix Error Code: InstructionFallbackNotFound?

Question

Today I had this error that took me a while to determine what was happening.

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       Is initialized!:
     Error: AnchorError occurred. Error Code: InstructionFallbackNotFound. Error Number: 101. Error Message: Fallback functions are not supported.
      at Function.parse (node_modules/@coral-xyz/anchor/src/error.ts:135:14)
      at translateError (node_modules/@coral-xyz/anchor/src/error.ts:276:35)
      at MethodsBuilder.rpc [as _rpcFn] (node_modules/@coral-xyz/anchor/src/program/namespace/rpc.ts:35:29)
      at processTicksAndRejections (node:internal/process/task_queues:95:5)

Answer 1

Check the name of the function in the anchor program

Check the name of the function is not a anchor/solana imported function

In my case, I fixed this issue by renaming the function as I had named it "crate" and there was an associated Anchor function that was crashing and resulting in this error.

In addition, i name another function like this: " start_here_ ", and the trailing " _ " was making me the same error, so renaming it without " _ " also can help you!