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

PromptTemplate.Builder.build() enforces that the template can come from exactly one source: an inline string template or a Resource. Setting both makes the source ambiguous, so build() throws this IllegalArgumentException.

Source

Thrown at spring-ai-model/src/main/java/org/springframework/ai/chat/prompt/PromptTemplate.java:260

			return this;
		}

		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;
		}

		public PromptTemplate 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 PromptTemplate(this.resource, this.variables, this.renderer);
			}
			else if (this.template != null) {
				return new PromptTemplate(this.template, this.variables, this.renderer);
			}
			else {
				throw new IllegalStateException("Neither template nor resource is set");
			}
		}

	}

}

View on GitHub (pinned to 98a7beda4f)

Solutions

1. Set only one source: remove the .template(...) call when using .resource(...), or vice versa.
2. If you want file-with-fallback, choose the source conditionally before building.
3. Create two separate builders instead of reusing one builder object for both variants.

Example fix

// before
PromptTemplate.builder().template("Hello {name}").resource(res).build();
// after
PromptTemplate.builder().resource(res).build();

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

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

When it happens

Trigger: Calling PromptTemplate.builder().template("...").resource(resource)...build() — i.e. both setters invoked on the same builder.

Common situations: Reusable builder code that unconditionally sets a default template and then optionally a resource file; copy-pasted fluent chains accumulating both sources.

Related errors

• Only one of template or resource can be set
• Only one of prompt or uri can be provided!
• Bean must not be null
• 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/5cae98387429d13d. Report an issue: GitHub.