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An API call that encounters an error will return 0 as its status code and display the cause of the error under the result field.

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Missing or Unsupported Chain

“Missing or unsupported chainid parameter (required for v2 api), please see chainlist for the list of supported chainids”
The chain you’ve specified is not supported by us yet. It could also be that you’ve sent multiple chains at the same time like 420, 10. You can only send one at a time.

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Invalid API Key

“Invalid API Key”
This error occurs when you specify an invalid API Key. Ensure you are using your Etherscan API Key, keys from other chains like Polygonscan/Arbiscan are not valid for V2. Keys do take a few minutes to activate. If it takes longer than 10 minutes, contact us.

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Too many invalid API key attempts

“Too many invalid api key attempts, please try again later”
This error occurs when more than 5 invalid API key attempts are made within a 30-second window. Your source IP will be temporarily throttled as a security measure. The throttle resets automatically after 30 seconds. To resolve, wait at least 30 seconds and retry with a valid API key.

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Max rate limit

“Max rate limit reached, please use API Key for higher rate limit”
This error occurs when you exceed the rate limit assigned to your specific API key. To resolve, adhere to the rate limits of your available plan. If you are using a script or application, apply throttling like a token bucket to limit the frequency of calls.

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Missing or invalid action

“Error! Missing Or invalid Action name”
This error occurs when you do not specify, or specify an invalid module and action name. To resolve, double check your API query to use a valid module and action name. This error can also occur when querying any Pro endpoint on a testnet network. Pro endpoints are only available to mainnet networks. For a full distinction between mainnet/testnet networks, consult our supported chains. If you require some help getting started, try copying the sample queries provided in the API Playground and pasting them into your browser.

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Endpoint-specific errors

“Error! Block number already pass”“Error! Invalid address format”“Contract source code not verified”
These error messages returned are specific to certain endpoints and their related parameters. To resolve, kindly refer to the specific endpoint’s documentation, and check for the correct format or values to be specified as parameters.

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Query Timeout

“Query Timeout occured. Please select a smaller result dataset”“Unexpected err, timeout occurred or server too busy. Please try again later”
This error occurs when you have sent a particularly large query that did not manage to be completed in time. To resolve, consider selecting a smaller date/block range, though you may ping us if you think the issue may be performance related.

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Free Tier Access

“Free API access is not supported for this chain. Please upgrade your api plan for full chain coverage.”
Certain chains are not included under the Free tier. To access all supported networks, you may upgrade to any of our paid plans, check out the affordable Lite tier.

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Community Free API Limit

“Community Free API limit reached. Resets 2026-06-24 12:00:00 UTC. For higher, uninterrupted limits, please upgrade to API Pro: https://etherscan.io/apis”
This error occurs when a chain ID’s shared pool of free API calls is fully used up. This limit is cumulative across all users of that pool, not tied to an individual API key. To resolve, wait until the quota resets at the specified time, or upgrade to a paid plan for higher, uninterrupted limits.