spring-projects/spring-ai · error · IllegalArgumentException

Only one of template or resource can be set

Error message

Only one of template or resource can be set

What it means

SystemPromptTemplate.Builder.build() throws this IllegalArgumentException when both an inline template and a Resource are set. Like PromptTemplate, the system-prompt variant requires exactly one template source.

Source

Thrown at spring-ai-model/src/main/java/org/springframework/ai/chat/prompt/SystemPromptTemplate.java:99

		}

		public Builder variables(Map<String, Object> variables) {
			Assert.notNull(variables, "variables cannot be null");
			Assert.noNullElements(variables.keySet(), "variables keys cannot be null");
			this.variables = variables;
			return this;
		}

		public Builder renderer(TemplateRenderer renderer) {
			Assert.notNull(renderer, "renderer cannot be null");
			this.renderer = renderer;
			return this;
		}

		@Override
		public SystemPromptTemplate build() {
			if (this.template != null && this.resource != null) {
				throw new IllegalArgumentException("Only one of template or resource can be set");
			}
			else if (this.resource != null) {
				return new SystemPromptTemplate(this.resource, this.variables, this.renderer);
			}
			else if (this.template != null) {
				return new SystemPromptTemplate(this.template, this.variables, this.renderer);
			}
			else {
				throw new IllegalStateException("Neither template nor resource is set");
			}
		}

	}

}

View on GitHub (pinned to 98a7beda4f)

Solutions

1. Remove either the .template(...) or the .resource(...) call so exactly one source remains.
2. Select the source conditionally (resource if configured, else inline) before building.
3. Use separate builder instances for the two variants.

Example fix

// before
SystemPromptTemplate.builder().template("You are helpful").resource(res).build();
// after
SystemPromptTemplate.builder().resource(res).build();

if (b.templateSet && b.resourceSet) throw new IllegalStateException("Set only one of template or resource for SystemPromptTemplate");

try { return builder.build(); } catch (IllegalArgumentException e) { logger.error("both template and resource set on SystemPromptTemplate", e); }

When it happens

Trigger: SystemPromptTemplate.builder().template("...").resource(resource)...build() — both sources configured on the same builder.

Common situations: Builder chains that set a default inline system prompt and then also attach a resource override; refactored code that kept a stale .template(...) call.

Related errors

• Only one of template or resource can be set
• Neither template nor resource is set
• Only one of prompt or uri can be provided!
• Bean must not be null
• Bean must not be null

AI-assisted analysis of spring-projects/spring-ai@98a7beda4f (2026-09-11). Data as JSON: /api/errors/6ea6f87ae196637f. Report an issue: GitHub.