Agent skill

Error Handling

Handle smart contract reverts and decode custom error types using Nethereum (.NET).

Install Error Handling

skills CLI

$ npx skills add Nethereum/Nethereum --skill error-handling -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install Nethereum/Nethereum error-handling --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/nethereum-skills/skills/error-handling .claude/skills/error-handling && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "error-handling" agent skill from https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling into .claude/skills/error-handling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "error-handling", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add Nethereum/Nethereum --skill error-handling -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install Nethereum/Nethereum error-handling --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/nethereum-skills/skills/error-handling .agents/skills/error-handling && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "error-handling" agent skill from https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling into .agents/skills/error-handling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "error-handling", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add Nethereum/Nethereum --skill error-handling -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install Nethereum/Nethereum error-handling --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/nethereum-skills/skills/error-handling .cursor/skills/error-handling && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "error-handling" agent skill from https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling into .cursor/skills/error-handling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "error-handling", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/Nethereum/Nethereum.git --path plugins/nethereum-skills/skills/error-handling

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add Nethereum/Nethereum --skill error-handling -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install Nethereum/Nethereum error-handling --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/nethereum-skills/skills/error-handling .gemini/skills/error-handling && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "error-handling" agent skill from https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling into .gemini/skills/error-handling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "error-handling", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install Nethereum/Nethereum error-handling

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add Nethereum/Nethereum --skill error-handling -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/nethereum-skills/skills/error-handling .github/skills/error-handling && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "error-handling" agent skill from https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling into .github/skills/error-handling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "error-handling", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add Nethereum/Nethereum --skill error-handling -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install Nethereum/Nethereum error-handling --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/nethereum-skills/skills/error-handling .opencode/skills/error-handling && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "error-handling" agent skill from https://github.com/Nethereum/Nethereum/tree/master/plugins/nethereum-skills/skills/error-handling into .opencode/skills/error-handling/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "error-handling", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: error-handling
GitHub stars: 2.3k
Token cost: ~1.1k tokens
SKILL.md length: 125 words
Files: 1
Skills in repo: 71
Repo updated: Oct 5, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Handle smart contract reverts and decode custom error types using Nethereum (.NET).

The user asks about contract errors
SKILL.md covers Define Custom Error DTOs, Catch and Decode a Specific…, Auto-Decode with… and Typed Exception Factory, plus 4 more sections
Calls dotnet
Custom Solidity errors

What it does

Error Handling is an agent skill from Nethereum/Nethereum. Handle smart contract reverts and decode custom error types using Nethereum (.NET). Use this skill whenever the user asks about contract errors, revert reasons, custom Solidity errors, SmartContractCustomErrorRevertException, error decoding, failed transaction reasons, or any revert handling in C/.NET.

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Backend & APIs, covering Smart contracts and Error handling. It works with .NET, C# and Solidity. The repository describes itself as: Ethereum .Net cross platform integration library. The licence is MIT.

When your agent uses it

The user asks about contract errors
Custom Solidity errors
SmartContractCustomErrorRevertException
Failed transaction reasons

Example prompts

“/error-handling”

What it can do on your machine

Read from SKILL.md and the folder at commit 229f278. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- dotnet
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Error Handling loads about 1.1k tokens when it runs. Until then it costs about 80 tokens; SKILL.md has 125 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~80
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Nethereum/Nethereum at commit 229f278, republished under its MIT licence (© Nethereum). 125 words, ~1,123 tokens.

Download SKILL.mdSave it as .claude/skills/error-handling/SKILL.md (or your agent's skills folder).

name: error-handling
description: Handle smart contract reverts and decode custom error types using Nethereum (.NET). Use this skill whenever the user asks about contract errors, revert reasons, custom Solidity errors, SmartContractCustomErrorRevertException, error decoding, failed transaction reasons, or any revert handling in C#/.NET.
user-invocable: true

Smart Contract Error Handling

NuGet: Nethereum.Web3

bash

dotnet add package Nethereum.Web3

Define Custom Error DTOs

Map Solidity custom errors to C# classes using [Error] and [Parameter] attributes.

csharp

using System.Numerics;
using Nethereum.ABI.FunctionEncoding.Attributes;
using Nethereum.Contracts;

// Solidity: error InsufficientBalance(address account, uint256 balance, uint256 required)
[Error("InsufficientBalance")]
public class InsufficientBalanceError
{
    [Parameter("address", "account", 1)]
    public string Account { get; set; }

    [Parameter("uint256", "balance", 2)]
    public BigInteger Balance { get; set; }

    [Parameter("uint256", "required", 3)]
    public BigInteger Required { get; set; }
}

// Solidity: error Unauthorized(address caller)
[Error("Unauthorized")]
public class UnauthorizedError
{
    [Parameter("address", "caller", 1)]
    public string Caller { get; set; }
}

Catch and Decode a Specific Error

csharp

try
{
    var receipt = await contractHandler
        .SendRequestAndWaitForReceiptAsync(transferFunction);
}
catch (SmartContractCustomErrorRevertException ex)
{
    if (ex.IsCustomErrorFor<InsufficientBalanceError>())
    {
        var error = ex.DecodeError<InsufficientBalanceError>();
        Console.WriteLine(
            $"Insufficient: {error.Account} has {error.Balance}, needs {error.Required}");
    }
    else if (ex.IsCustomErrorFor<UnauthorizedError>())
    {
        var error = ex.DecodeError<UnauthorizedError>();
        Console.WriteLine($"Unauthorized: {error.Caller}");
    }
}

Auto-Decode with ContractServiceBase

Code-generated contract services register all error types. Use FindCustomErrorException():

csharp

catch (SmartContractCustomErrorRevertException ex)
{
    var typedException = myContractService.FindCustomErrorException(ex);
    if (typedException != null)
    {
        Console.WriteLine($"Error: {typedException.DecodedError}");
        Console.WriteLine($"Error ABI: {typedException.ErrorABI.Name}");
    }
}

Typed Exception Factory

csharp

var errorTypes = new[] { typeof(InsufficientBalanceError), typeof(UnauthorizedError) };

catch (SmartContractCustomErrorRevertException ex)
{
    var typed = SmartContractCustomErrorTypedFactory.CreateTypedException(ex, errorTypes);
    if (typed is SmartContractCustomErrorRevertException<InsufficientBalanceError> balanceEx)
    {
        var error = balanceEx.CustomError;
        Console.WriteLine($"Need {error.Required}, have {error.Balance}");
    }
}

Get Error Reason from Failed Transaction

csharp

var errorReason = await web3.Eth.GetContractTransactionErrorReason
    .SendRequestAsync(failedTransactionHash);
Console.WriteLine($"Transaction failed: {errorReason}");

Decode Error from Raw Hex Data

csharp

var exception = new SmartContractCustomErrorRevertException(hexEncodedErrorData);
if (exception.IsCustomErrorFor<InsufficientBalanceError>())
{
    var error = exception.DecodeError<InsufficientBalanceError>();
}

Key Types

SmartContractCustomErrorRevertException -- base exception with ExceptionEncodedData
SmartContractCustomErrorRevertException<TError> -- generic typed with CustomError property
SmartContractCustomErrorRevertExceptionErrorDecoded -- decoded with DecodedError string
SmartContractCustomErrorTypedFactory -- factory for typed exceptions from error type list
ContractServiceBase.FindCustomErrorException() -- auto-decode using registered types
web3.Eth.GetContractTransactionErrorReason -- error reason from mined failed tx

Common Patterns

Task	Method
Check error type	`ex.IsCustomErrorFor<TError>()`
Decode to typed object	`ex.DecodeError<TError>()`
Decode to default string	`ex.DecodeErrorToDefaultString(errorABI)`
Auto-decode from service	`contractService.FindCustomErrorException(ex)`
Factory decode	`SmartContractCustomErrorTypedFactory.CreateTypedException(ex, types)`
Error from failed tx	`web3.Eth.GetContractTransactionErrorReason.SendRequestAsync(hash)`

Files

Just SKILL.md in plugins/nethereum-skills/skills/error-handling of Nethereum/Nethereum.

Open the folder on GitHubat commit 229f278

Compare with similar skills

Error Handling next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Error Handling compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Error Handling this skillNethereum/Nethereum	2.3k	—	~1.1k	Automated safety check: Pass	MIT	4 days ago
Error Handlingccashwell/evm-cortex	131	—	~1.7k	Automated safety check: Pass	MIT	9 days ago
Akka.NET Best PracticesAaronontheweb/dotnet-skills	1.2k	1 repos	~3.3k	Automated safety check: Pass	MIT	21 days ago
Fizz Convertpashov/skills	1.2k	2 repos	~3.7k	Automated safety check: Pass	MIT	4 days ago
Feynman Auditor0xiehnnkta/nemesis-auditor	243	1 repos	~11k	Automated safety check: Pass	MIT	6 mo ago
Smart Contract Auditgreatpie/smart-contract-audit-skill	101	—	~1.1k	Automated safety check: Pass	None	7 mo ago

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Works with

Questions about Error Handling

What does Error Handling do?

Handle smart contract reverts and decode custom error types using Nethereum (.NET). Error Handling is an agent skill from Nethereum/Nethereum.NET).

When should I use Error Handling?

Error Handling fits situations like: the user asks about contract errors; custom Solidity errors; smartContractCustomErrorRevertException; failed transaction reasons.

How do I install Error Handling in Claude Code?

Run `npx skills add Nethereum/Nethereum --skill error-handling -a claude-code`. Or copy the skill folder (plugins/nethereum-skills/skills/error-handling in Nethereum/Nethereum) into .claude/skills/error-handling in your project. Claude Code loads it when a task matches its description.

How do I install Error Handling in Codex?

Run `npx skills add Nethereum/Nethereum --skill error-handling -a codex`. Or copy the skill folder (plugins/nethereum-skills/skills/error-handling in Nethereum/Nethereum) into .agents/skills/error-handling in your project. Codex loads it when a task matches its description.

Can I use Error Handling in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add Nethereum/Nethereum --skill error-handling -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/error-handling, .gemini/skills/error-handling, .github/skills/error-handling and .opencode/skills/error-handling in your project.

What does Error Handling need to run?

Going by SKILL.md and its folder, Error Handling needs the command-line tools its instructions call (dotnet).

Does Error Handling access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Error Handling safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Error Handling use?

Error Handling is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Error Handling use?

About 1.1k tokens (SKILL.md is roughly 4.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Error Handling?

Skills that share tags, products or a category with Error Handling: Error Handling (ccashwell/evm-cortex, 131 stars), Akka.NET Best Practices (Aaronontheweb/dotnet-skills, 1.2k stars), Fizz Convert (pashov/skills, 1.2k stars) and Feynman Auditor (0xiehnnkta/nemesis-auditor, 243 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Error Handling?

Nethereum (a GitHub organization) maintains it in Nethereum/Nethereum, which has 2,260 GitHub stars. The repository holds 71 skills in this directory. The repository was last updated on October 5, 2026.

Source: Nethereum/Nethereum on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Error Handling

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Smart Contract Error Handling

Define Custom Error DTOs

Catch and Decode a Specific Error

Auto-Decode with ContractServiceBase

Typed Exception Factory

Get Error Reason from Failed Transaction

Decode Error from Raw Hex Data

Key Types

Common Patterns

Files

Compare with similar skills

Similar skills

More from Nethereum/Nethereum

Related

Questions about Error Handling