What causes "Block not found: ${blockId}" in wavetermdev/waveterm?

Verify the blockId still exists (via the tab's block list / getfocusedblockdata) before calling

Block not found: ${blockId}

Error message

Block not found: ${blockId}

What it means

captureBlockScreenshot resolved the tab's LayoutModel, but layoutModel.getNodeByBlockId(blockId) returned null — the given blockId does not exist in this tab's layout tree. The screenshot can only be taken from blocks actually rendered in the current tab, so an unknown blockId is rejected.

Source

Thrown at frontend/app/store/tabrpcclient.ts:30

export class TabClient extends WshClient {
    constructor(routeId: string) {
        super(routeId);
    }

    handle_captureblockscreenshot(rh: RpcResponseHelper, data: CommandCaptureBlockScreenshotData): Promise<string> {
        return this.captureBlockScreenshot(data.blockid);
    }

    async captureBlockScreenshot(blockId: string): Promise<string> {
        const layoutModel = getLayoutModelForStaticTab();
        if (!layoutModel) {
            throw new Error("Layout model not found");
        }

        const node = layoutModel.getNodeByBlockId(blockId);
        if (!node) {
            throw new Error(`Block not found: ${blockId}`);
        }

        const displayContainer = layoutModel.displayContainerRef.current;
        if (!displayContainer) {
            throw new Error("Display container not found");
        }

        const containerRect = displayContainer.getBoundingClientRect();
        const additionalProps = layoutModel.getNodeAdditionalProperties(node);

        let electronRect: Electron.Rectangle;

        if (!additionalProps?.rect) {
            // Bug: rect is not set when there is only one block in the layout
            // In this case, use the full container rect
            electronRect = {
                x: Math.round(containerRect.x),
                y: Math.round(containerRect.y),

View on GitHub (pinned to a4447c1563)

Solutions

Verify the blockId still exists (via the tab's block list / getfocusedblockdata) before calling
Ensure the RPC is sent on the TabRpcClient of the tab that owns the block
Listen for block-close/delete events and purge cached blockIds
Log the tabId+blockId pair to confirm they match the tab receiving the RPC

Example fix

// before
await rpcService.call("captureblockscreenshot", { blockid: cachedBlockId });
// after
if (globalStore.get(tabLayoutModel.nodeMap).some((n) => n.data?.blockId === cachedBlockId)) {
    await rpcService.call("captureblockscreenshot", { blockid: cachedBlockId });
} else {
    cachedBlockId = null;
}

Defensive patterns

Strategy: validation

Validate before calling

const node = layoutModel?.getNodeByBlockId(blockId);
if (!node) {
    console.warn("skipping capture, block not in this tab:", blockId);
    return null;
}

Type guard

function blockExistsInTab(blockId: string): boolean {
    return getLayoutModelForStaticTab()?.getNodeByBlockId(blockId) != null;
}

Try / catch

try {
    const pngData = await rpcService.call("captureblockscreenshot", { blockid });
} catch (e) {
    if (String(e).startsWith("Block not found:")) {
        purgeCachedBlockId(blockid);
        return null;
    }
    throw e;
}

Prevention

Subscribe to block close/delete events and drop cached ids
Route block-specific RPCs through the owning tab's TabRpcClient
Never persist blockIds across workspace restores without revalidation

When it happens

Trigger: handle_captureblockscreenshot called with a blockId that was closed, belongs to a different tab/window, was never created, or whose id string is malformed.

Common situations: Client caches blockIds and screenshots a block the user already closed; a UUID from another tab (blockIds are per-tab layout in this call path); typos or stale ids persisted in app state across reloads.

Related errors

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/76931e694c5eb93b. Report an issue: GitHub.