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Unexpected Behavior: Interrupt() when invoked for the second time, failed to wait for the user input #157

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opened 2026-02-15 17:16:32 -05:00 by yindo · 4 comments
yindo commented 2026-02-15 17:16:32 -05:00
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Originally created by @shtanko-michael on GitHub (Jan 21, 2025).

Originally assigned to: @benjamincburns on GitHub.

Description
I am using interrupt function inside a subgraph, the first time it works as expected, it terminates the graph execution and I can type text in the console. But after I resume the graph and call interrupt for the second (or more) time, it returns the same previously cached value. So it does not work as expected.
When I remove the subgraph and implement the same logic inside parent graph, it works fine, so I think it is a bug, and also I found some discussions here on Github explaining this behavior and a way to fix it, hope this helps!

https://github.com/langchain-ai/langgraph/issues/3072
https://github.com/langchain-ai/langgraph/compare/main...vigneshmj1997:langgraph:interrupt_patch_for_subgraph

As far as I understand it fixed in 0.2.63 in Python Langgraph repo

Code

import { StateGraph, Annotation, START, MessagesAnnotation, Command, interrupt, MemorySaver, END } from "@langchain/langgraph";
import dotenv from "dotenv";
import { HumanMessage, AIMessage } from "@langchain/core/messages";
import readline from 'readline';
import { v4 } from 'uuid';

let rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

dotenv.config();

const SugGraphStateAnnotation = Annotation.Root({
    ...MessagesAnnotation.spec,
    counter: Annotation<number>,
    caller: Annotation<string | null>
});

const askHuman = async (state: typeof SugGraphStateAnnotation.State) => {
    const humanMessage = interrupt({
        'id': v4(),
        'request': state.messages[state.messages.length - 1].content,
    }) as string;

    console.log('Execution=', state.counter, 'Human message=', humanMessage);

    return new Command({
        goto: state.caller ?? END,
        update: {
            messages: [new HumanMessage({ content: humanMessage, name: 'askHuman' })],
            caller: null
        },
    });
}

const initial = async (state: typeof SugGraphStateAnnotation.State) => {
    return new Command({
        goto: 'askHuman',
        update: {
            caller: 'initial',
            counter: state.counter + 1,
            messages: [new AIMessage({ content: 'Question to ask user', name: 'initial' })]
        }
    });
};

const subGraphWorkflow = new StateGraph(SugGraphStateAnnotation)
    .addNode("askHuman", askHuman)
    .addNode("initial", initial, { ends: ['askHuman', END] })
    .addEdge(START, "initial");

const subGraph = subGraphWorkflow.compile();


const ParentStateAnnotation = MessagesAnnotation;
const router = (state: typeof ParentStateAnnotation.State) => {
    return new Command({
        goto: 'subGraph',
        update: {
            caller: 'router',
            messages: [new AIMessage({ content: 'Go to subgraph', name: 'router' })]
        }
    });
}

const parentGraphWorkflow = new StateGraph(ParentStateAnnotation)
    .addNode("router", router, { ends: ['subGraph'] })
    .addNode("subGraph", subGraph)
    .addEdge(START, "router");

const checkpointer = new MemorySaver();

const parentGraph = parentGraphWorkflow.compile({ checkpointer });

const config = { configurable: { thread_id: "console_app" } };

async function main() {
    try {
        await parentGraph.invoke({
            messages: [
                new HumanMessage("Inital message")
            ]
        }, config);

        const state = await parentGraph.getState(config);
        console.log((JSON.stringify(state.values, null, 2)));

        while (true) {
            const answer = await askQuestion();

            await resumeGraph(answer);
        }
    } catch (error) {
        console.error("An error occurred:", error);
    } finally {
        rl.close();
    }
}

async function askQuestion(): Promise<string> {
    return new Promise(function (resolve, reject) {
        rl.question("\User answer: ", async function (answer) {
            resolve(answer);
            rl.close();
        });
    });
}

async function resumeGraph(answer: string) {
    await parentGraph.invoke(new Command({ resume: answer }), config)
}

main();

Output

User answer: test answer
Execution= 1 Human message= test answer
Execution= 2 Human message= test answer
Execution= 3 Human message= test answer
Execution= 4 Human message= test answer
Execution= 5 Human message= test answer
Execution= 6 Human message= test answer
Execution= 7 Human message= test answer
Execution= 8 Human message= test answer
Execution= 9 Human message= test answer
Execution= 10 Human message= test answer
Execution= 11 Human message= test answer
Execution= 12 Human message= test answer
Execution= 13 Human message= test answer
Execution= 14 Human message= test answer

An error occurred: GraphRecursionError: Recursion limit of 25 reached without hitting a stop condition. You can increase the limit by setting the "recursionLimit" config key.

Troubleshooting URL: https://js.langchain.com/docs/troubleshooting/errors/GRAPH_RECURSION_LIMIT/

    at CompiledStateGraph._runLoop (file:///C:/projects/talkapp-ai/langchain/node_modules/.pnpm/@langchain+langgraph@0.2.41_@langchain+core@0.3.30_openai@4.78.1_zod@3.24.1__/node_modules/@langchain/langgraph/dist/pregel/index.js:887:23)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async createAndRunLoop (file:///C:/projects/talkapp-ai/langchain/node_modules/.pnpm/@langchain+langgraph@0.2.41_@langchain+core@0.3.30_openai@4.78.1_zod@3.24.1__/node_modules/@langchain/langgraph/dist/pregel/index.js:980:17) {
  lc_error_code: 'GRAPH_RECURSION_LIMIT',
  pregelTaskId: 'd90e7254-46a7-582c-90d7-1fea82c89f52'
}
Originally created by @shtanko-michael on GitHub (Jan 21, 2025). Originally assigned to: @benjamincburns on GitHub. **Description** I am using `interrupt` function inside a subgraph, the first time it works as expected, it terminates the graph execution and I can type text in the console. But after I resume the graph and call `interrupt` for the second (or more) time, it returns the same previously cached value. So it does not work as expected. When I remove the subgraph and implement the same logic inside parent graph, it works fine, so I think it is a bug, and also I found some discussions here on Github explaining this behavior and a way to fix it, hope this helps! https://github.com/langchain-ai/langgraph/issues/3072 https://github.com/langchain-ai/langgraph/compare/main...vigneshmj1997:langgraph:interrupt_patch_for_subgraph As far as I understand it fixed in [0.2.63](https://github.com/langchain-ai/langgraph/releases/tag/0.2.63) in Python Langgraph repo **Code** ```ts import { StateGraph, Annotation, START, MessagesAnnotation, Command, interrupt, MemorySaver, END } from "@langchain/langgraph"; import dotenv from "dotenv"; import { HumanMessage, AIMessage } from "@langchain/core/messages"; import readline from 'readline'; import { v4 } from 'uuid'; let rl = readline.createInterface({ input: process.stdin, output: process.stdout }); dotenv.config(); const SugGraphStateAnnotation = Annotation.Root({ ...MessagesAnnotation.spec, counter: Annotation<number>, caller: Annotation<string | null> }); const askHuman = async (state: typeof SugGraphStateAnnotation.State) => { const humanMessage = interrupt({ 'id': v4(), 'request': state.messages[state.messages.length - 1].content, }) as string; console.log('Execution=', state.counter, 'Human message=', humanMessage); return new Command({ goto: state.caller ?? END, update: { messages: [new HumanMessage({ content: humanMessage, name: 'askHuman' })], caller: null }, }); } const initial = async (state: typeof SugGraphStateAnnotation.State) => { return new Command({ goto: 'askHuman', update: { caller: 'initial', counter: state.counter + 1, messages: [new AIMessage({ content: 'Question to ask user', name: 'initial' })] } }); }; const subGraphWorkflow = new StateGraph(SugGraphStateAnnotation) .addNode("askHuman", askHuman) .addNode("initial", initial, { ends: ['askHuman', END] }) .addEdge(START, "initial"); const subGraph = subGraphWorkflow.compile(); const ParentStateAnnotation = MessagesAnnotation; const router = (state: typeof ParentStateAnnotation.State) => { return new Command({ goto: 'subGraph', update: { caller: 'router', messages: [new AIMessage({ content: 'Go to subgraph', name: 'router' })] } }); } const parentGraphWorkflow = new StateGraph(ParentStateAnnotation) .addNode("router", router, { ends: ['subGraph'] }) .addNode("subGraph", subGraph) .addEdge(START, "router"); const checkpointer = new MemorySaver(); const parentGraph = parentGraphWorkflow.compile({ checkpointer }); const config = { configurable: { thread_id: "console_app" } }; async function main() { try { await parentGraph.invoke({ messages: [ new HumanMessage("Inital message") ] }, config); const state = await parentGraph.getState(config); console.log((JSON.stringify(state.values, null, 2))); while (true) { const answer = await askQuestion(); await resumeGraph(answer); } } catch (error) { console.error("An error occurred:", error); } finally { rl.close(); } } async function askQuestion(): Promise<string> { return new Promise(function (resolve, reject) { rl.question("\User answer: ", async function (answer) { resolve(answer); rl.close(); }); }); } async function resumeGraph(answer: string) { await parentGraph.invoke(new Command({ resume: answer }), config) } main(); ``` **Output** ``` User answer: test answer Execution= 1 Human message= test answer Execution= 2 Human message= test answer Execution= 3 Human message= test answer Execution= 4 Human message= test answer Execution= 5 Human message= test answer Execution= 6 Human message= test answer Execution= 7 Human message= test answer Execution= 8 Human message= test answer Execution= 9 Human message= test answer Execution= 10 Human message= test answer Execution= 11 Human message= test answer Execution= 12 Human message= test answer Execution= 13 Human message= test answer Execution= 14 Human message= test answer An error occurred: GraphRecursionError: Recursion limit of 25 reached without hitting a stop condition. You can increase the limit by setting the "recursionLimit" config key. Troubleshooting URL: https://js.langchain.com/docs/troubleshooting/errors/GRAPH_RECURSION_LIMIT/ at CompiledStateGraph._runLoop (file:///C:/projects/talkapp-ai/langchain/node_modules/.pnpm/@langchain+langgraph@0.2.41_@langchain+core@0.3.30_openai@4.78.1_zod@3.24.1__/node_modules/@langchain/langgraph/dist/pregel/index.js:887:23) at process.processTicksAndRejections (node:internal/process/task_queues:105:5) at async createAndRunLoop (file:///C:/projects/talkapp-ai/langchain/node_modules/.pnpm/@langchain+langgraph@0.2.41_@langchain+core@0.3.30_openai@4.78.1_zod@3.24.1__/node_modules/@langchain/langgraph/dist/pregel/index.js:980:17) { lc_error_code: 'GRAPH_RECURSION_LIMIT', pregelTaskId: 'd90e7254-46a7-582c-90d7-1fea82c89f52' } ```
yindo closed this issue 2026-02-15 17:16:33 -05:00
yindo commented 2026-02-15 17:16:33 -05:00
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@zhibinyang commented on GitHub (Jan 22, 2025):

I saw same issue since I started using subgraph, originally I thought there's some workaround, until today, I tried everything but could not get a solution, then I see this issue (as well as python versions').
Really hope to see a fix.

@zhibinyang commented on GitHub (Jan 22, 2025): I saw same issue since I started using subgraph, originally I thought there's some workaround, until today, I tried everything but could not get a solution, then I see this issue (as well as python versions'). Really hope to see a fix.
yindo commented 2026-02-15 17:16:34 -05:00
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@PieNam commented on GitHub (Feb 25, 2025):

No update on this issue, not mentioned in the changelog neither, but after bumping into "@langchain/langgraph": "~0.2.49" and testing again, it seems like this issue is fixed 🤔 (before was troubled by 0.2.41)

@PieNam commented on GitHub (Feb 25, 2025): No update on this issue, not mentioned in the changelog neither, but after bumping into `"@langchain/langgraph": "~0.2.49"` and testing again, it seems like this issue is fixed 🤔 (before was troubled by 0.2.41)
yindo commented 2026-02-15 17:16:34 -05:00
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@saqibshamsi commented on GitHub (Mar 13, 2025):

I am on langgraph 0.3.7 and facing this issue.

@saqibshamsi commented on GitHub (Mar 13, 2025): I am on langgraph `0.3.7` and facing this issue.
yindo commented 2026-02-15 17:16:34 -05:00
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@benjamincburns commented on GitHub (Mar 13, 2025):

@shtanko-michael as of the latest release (0.2.55) the code that you included in your initial description executes correctly. I'm not sure if it's intended in your example, but there is an infinite loop where your subgraph is always directing back to the router node, which is always directing back to the subgraph. This means that it will keep interrupting forever, but it does actually interrupt now rather than consuming the same resume value over and over again.

@zhibinyang @PieNam @saqibshamsi please update to latest version. If you're still having problems, please open a new issue with a code sample that reflects the issue that you're having.

@benjamincburns commented on GitHub (Mar 13, 2025): @shtanko-michael as of the latest release (0.2.55) the code that you included in your initial description executes correctly. I'm not sure if it's intended in your example, but there is an infinite loop where your subgraph is always directing back to the router node, which is always directing back to the subgraph. This means that it will keep interrupting forever, but it does actually interrupt now rather than consuming the same resume value over and over again. @zhibinyang @PieNam @saqibshamsi please update to latest version. If you're still having problems, please open a new issue with a code sample that reflects the issue that you're having.
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Reference: langchain-ai/langgraphjs#157
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