microsoft/vscode · error · Error

Unable to build prompt, modelMaxPromptTokens = ${maxTokens}

Error message

Unable to build prompt, modelMaxPromptTokens = ${maxTokens} (${e.message})

What it means

Error "Unable to build prompt, modelMaxPromptTokens = ${maxTokens} (${e.message})" thrown in microsoft/vscode.

Source

Thrown at extensions/copilot/src/extension/intents/node/agentIntent.ts:842

		}

		// Render the prompt without summarization or cache breakpoints, using
		// the original endpoint (not reduced for tools/safety buffer).
		const renderWithoutSummarization = async (reason: string, renderProps: AgentPromptProps = props): Promise<RenderPromptResult> => {
			this.logService.debug(`[Agent] ${reason}, rendering without summarization`);
			const renderer = PromptRenderer.create(this.instantiationService, this.endpoint, this.prompt, {
				...renderProps,
				endpoint: this.endpoint,
				enableSummarization: false,
				enableCacheBreakpoints: false
			});
			try {
				return await renderer.render(progress, token);
			} catch (e) {
				if (e instanceof BudgetExceededError) {
					this.logService.error(e, `[Agent] fallback render failed due to budget exceeded`);
					const maxTokens = this.endpoint.modelMaxPromptTokens;
					throw new Error(`Unable to build prompt, modelMaxPromptTokens = ${maxTokens} (${e.message})`);
				}
				throw e;
			}
		};

		// Helper function for synchronous summarization flow with fallbacks
		const renderWithSummarization = async (reason: string, renderProps: AgentPromptProps = props): Promise<RenderPromptResult> => {
			// Check if a previous foreground summarization already failed in this
			// turn.  The metadata is set on the turn returned by getLatestTurn(),
			// which is the same turn throughout a single buildPrompt call since
			// the conversation doesn't advance mid-render.
			const turn = promptContext.conversation?.getLatestTurn();
			const previousForegroundSummary = turn?.getMetadata(SummarizedConversationHistoryMetadata);
			if (previousForegroundSummary?.source === 'foreground' && previousForegroundSummary.outcome && previousForegroundSummary.outcome !== 'success') {
				this.logService.debug(`[ConversationHistorySummarizer] ${reason}, skipping repeated foreground summarization after prior failure (${previousForegroundSummary.outcome})`);
				/* __GDPR__
					"triggerSummarizeSkipped" : {
						"owner": "bhavyau",

View on GitHub (pinned to a94b963a32)

When it happens

Trigger: Thrown at extensions/copilot/src/extension/intents/node/agentIntent.ts:842 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/vscode@a94b963a32 (2026-08-12). Data as JSON: /api/errors/b1832fd24f393105. Report an issue: GitHub.