alibaba/spring-cloud-alibaba · error · IllegalStateException

{type} create fail

Error message

{type} create fail

What it means

If the resolved fallback instance is itself a Spring FactoryBean, SentinelFeign calls getObject() to obtain the real instance. When that call throws, the exception is wrapped in this IllegalStateException ('{type} create fail'), where {type} is fallback or fallbackFactory. It surfaces a failure inside the factory bean, not in Sentinel itself.

Source

Thrown at spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-sentinel/src/main/java/com/alibaba/cloud/sentinel/feign/SentinelFeign.java:162

						Class fallbackType, Class targetType) {
					FeignClientFactory factory = Builder.this.feignClientFactory;
					if (factory == null) {
						throw new IllegalStateException("FeignClientFactory not initialized");
					}
					Object fallbackInstance = factory.getInstance(name,
							fallbackType);
					if (fallbackInstance == null) {
						throw new IllegalStateException(String.format(
								"No %s instance of type %s found for feign client %s",
								type, fallbackType, name));
					}
					// when fallback is a FactoryBean, should determine the type of instance
					if (fallbackInstance instanceof FactoryBean<?> factoryBean) {
						try {
							fallbackInstance = factoryBean.getObject();
						}
						catch (Exception e) {
							throw new IllegalStateException(type + " create fail", e);
						}
						if (fallbackInstance == null) {
							throw new IllegalStateException(type + " FactoryBean returned null");
						}
						fallbackType = fallbackInstance.getClass();
					}

					if (!targetType.isAssignableFrom(fallbackType)) {
						throw new IllegalStateException(String.format(
								"Incompatible %s instance. Fallback/fallbackFactory of type %s is not assignable to %s for feign client %s",
								type, fallbackType, targetType, name));
					}
					return fallbackInstance;
				}
			});

			super.contract(new SentinelContractHolder(contract));
			return super.internalBuild();

View on GitHub (pinned to 115d590110)

Solutions

  1. Inspect the wrapped cause (the original Exception) to find the real failure in getObject().
  2. Ensure all dependencies the FactoryBean needs are available and initialized before the feign client is built.
  3. Fix or replace the failing FactoryBean; if it cannot reliably produce instances, use a plain @Component fallback instead.
  4. Reproduce getObject() in a unit test against the FactoryBean in isolation.
Defensive patterns

Strategy: try-catch

Validate before calling

Object safeGetObject(FactoryBean<?> fb) {
  try { return fb.getObject(); }
  catch (Exception e) { throw new IllegalStateException("FactoryBean getObject failed for " + fb.getClass(), e); }
}

Try / catch

try { inst = factoryBean.getObject(); }
catch (Exception e) { log.error("fallback factory bean failed", e); /* fall back to default or fail fast */ throw e; }

Prevention

When it happens

Trigger: A fallback declared as a FactoryBean whose getObject() throws (e.g. fails to construct the target, hits a downstream dependency, or returns based on missing config).

Common situations: A FactoryBean that depends on resources not yet initialized. A protobuf/proxy FactoryBean that fails to build the proxy. Misconfigured factory bean properties.

Related errors

AI-assisted analysis of alibaba/spring-cloud-alibaba@115d590110 (2026-08-14). Data as JSON: /api/errors/cb70d98d15130d07. Report an issue: GitHub.