Question Re: Error 500 in CAP entitySet READ in Technology Q&A

Error 500 in CAP entitySet READ

ZMoe — Tue, 14 Oct 2025 05:27:39 GMT

Hi everyone, I'm new to CAP development. I ran into this problem when building a simple demo in the trial environment.

I have successfully deployed my CAP application to BTP and can access the service metadata.

https://xxxtrial-dev-moe-cap-backend-srv.cfapps.us10-001.hana.ondemand.com/odata/v4/My_SRV/$metadata

But when I access the entitySet, I get the following error:

https://xxxtrial-dev-moe-cap-backend-srv.cfapps.us10-001.hana.ondemand.com/odata/v4/My_SRV/MoeSet

I generated the CAP framework using the following command:

mvn -B archetype:generate -DarchetypeArtifactId=cds-services-archetype -DarchetypeGroupId=com.sap.cds -DarchetypeVersion=RELEASE -DgroupId=com.moe.company -DartifactId=moe-cap-backend -Dpackage=com.moe.company.moecapbackend

Then I created capservice.cds under the srv directory with the following content:

service My_SRV { @requires: 'any' entity MoeSet as projection on TestSet; } entity TestSet { key testKey : String(64); inputData : String(100); memo: String(100); outputData: String(100); }

And I also created a MyServiceHandler.java file under the main directory with the following content:

package com.moe.company.mycapbackend; import java.util.HashMap; import java.util.Map; import com.sap.cds.services.cds.CdsReadEventContext; import com.sap.cds.services.cds.CqnService; import com.sap.cds.services.handler.EventHandler; import com.sap.cds.services.handler.annotations.On; import com.sap.cds.services.handler.annotations.ServiceName; import com.sap.cds.services.request.UserInfo; import cds.gen.my_srv.MoeSet; @ServiceName("My_SRV") public class MyServiceHandler implements EventHandler { @On(event = CqnService.EVENT_READ, entity = "My_SRV.MoeSet") public void beforeReadProducts(CdsReadEventContext context) { UserInfo userInfo = context.getUserInfo(); MoeSet datamodel = com.sap.cds.Struct.create(MoeSet.class); datamodel.put(MoeSet.MEMO, userInfo.getName()); Map<Object, Map<String, Object>> result = new HashMap<>(); String key ="test1"; result.put(key, datamodel); context.setResult(result.values()); } }

Since this is just a simple practice, I didn't add authentication. Here's my mta.yaml file:

_schema-version: 3.3.0 ID: moe-cap-backend version: 1.0.0-SNAPSHOT description: "A simple CAP project." parameters: enable-parallel-deployments: true modules: - name: moe-cap-backend-srv type: java path: srv parameters: instances: 1 buildpack: sap_java_buildpack_jakarta properties: SPRING_PROFILES_ACTIVE: cloud,sandbox JBP_CONFIG_COMPONENTS: "jres: ['com.sap.xs.java.buildpack.jre.SAPMachineJRE']" JBP_CONFIG_SAP_MACHINE_JRE: '{ version: 17.+ }' build-parameters: builder: custom commands: - mvn clean package -DskipTests=true --batch-mode build-result: target/*-exec.jar provides: - name: srv-api # required by consumers of CAP services (e.g. approuter) properties: srv-url: ${default-url}

Are there any steps I might have missed?

Re: Error 500 in CAP entitySet READ

MioYasutake — Tue, 14 Oct 2025 10:17:00 GMT

@ZMoe

A 500 error when accessing an entity typically occurs when the HANA Cloud is stopped. Can you verify that your HANA Cloud instance is running?

Re: Error 500 in CAP entitySet READ

ZMoe — Wed, 15 Oct 2025 01:52:48 GMT

Yasutake-san, thank you for your reply. Since this exercise is simple demo, so I haven't prepared to use it for updating HANA DB data yet. Is HANADB configuration mandatory for CAP program deployment anyway?(even if I won't use it for data updates?)

Re: Error 500 in CAP entitySet READ

MioYasutake — Wed, 15 Oct 2025 10:55:17 GMT

@ZMoe Sorry, I overlooked that your app doesn't use DB. In that case, HANA Cloud is not required. Do you see any detailed errors in the service log (retrieved via cf logs moe-cap-backend-srv)?

Re: Error 500 in CAP entitySet READ

ZMoe — Thu, 16 Oct 2025 07:11:34 GMT

@MioYasutake

Thank you for your advice.

I checked the logs.

😢Even though the code doesn't get or update data from the database, according to the log, it seems the CAP backend still tried to connect to some database.

I copied part of the log:

2025-10-16T06:57:39.471+0000 [APP/PROC/WEB/0] STDOUT com.sap.cds.services.impl.ContextualizedServiceException: Error executing the statement (service 'PersistenceService$Default', event 'READ', entity 'My_SRV.MoeSet') 2025-10-16T06:57:39.471+0000 [APP/PROC/WEB/0] STDOUT at com.sap.cds.services.impl.ServiceImpl.dispatch(ServiceImpl.java:269) ~[cds-services-impl-4.4.1.jar:na] 2025-10-16T06:57:39.471+0000 [APP/PROC/WEB/0] STDOUT at com.sap.cds.services.impl.ServiceImpl.emit(ServiceImpl.java:180) ~[cds-services-impl-4.4.1.jar:na] 2025-10-16T06:57:39.471+0000 [APP/PROC/WEB/0] STDOUT at com.sap.cds.services.ServiceDelegator.emit(ServiceDelegator.java:33) ~[cds-services-api-4.4.1.jar:na] 2025-10-16T06:57:39.471+0000 [APP/PROC/WEB/0] STDOUT at com.sap.cds.services.utils.services.AbstractCqnService.run(AbstractCqnService.java:64) ~[cds-services-utils-4.4.1.jar:na] ======================= 2025-10-16T06:57:39.472+0000 [APP/PROC/WEB/0] STDOUT Caused by: com.sap.cds.CdsDataStoreException: SQL: SELECT T0."TESTKEY", T0."INPUTDATA", T0."MEMO", T0."OUTPUTDATA" FROM "MY_SRV_MOESET" T0 ORDER BY T0."TESTKEY" NULLS FIRST LIMIT 1000 2025-10-16T06:57:39.472+0000 [APP/PROC/WEB/0] STDOUT ... 126 common frames omitted 2025-10-16T06:57:39.472+0000 [APP/PROC/WEB/0] STDOUT Caused by: org.h2.jdbc.JdbcSQLSyntaxErrorException: Table "MY_SRV_MOESET" not found (this database is empty); SQL statement: 2025-10-16T06:57:39.472+0000 [APP/PROC/WEB/0] STDOUT SELECT T0."TESTKEY", T0."INPUTDATA", T0."MEMO", T0."OUTPUTDATA" FROM "MY_SRV_MOESET" T0 ORDER BY T0."TESTKEY" NULLS FIRST LIMIT 1000 [42104-232]

And I updated some code today. I added READ and CREATE methods.

But after I deployed it again, I got the same error.

*Even though it's a very simple example, I put the code on Git for now as a reference: https://github.com/moez-1217/moe-cap.git

Re: Error 500 in CAP entitySet READ

ZMoe — Thu, 16 Oct 2025 08:00:47 GMT

Thank you for your advice. I checked the logs. Even though the code doesn't get or update data from the database, according to the log, it seems the CAP backend still tried to connect to some database.I copied part of the log:

Re: Error 500 in CAP entitySet READ

MioYasutake — Thu, 16 Oct 2025 20:26:56 GMT

@ZMoe

If you don't use a database, try adding the following profile to the application.yaml.

--- spring: config: activate: on-profile: cloud cds: data-source: auto-config: enabled: false

Re: Error 500 in CAP entitySet READ

ZMoe — Mon, 20 Oct 2025 07:03:53 GMT

@MioYasutake Thank you for your reply.

My application.yaml was automatically generated with the same content as yours. So maybe it shouldn't be the issue here.

I later tried some other methods to fix the error mentioned above. Finally, I resolved it using the approach below (at least that error no longer appears, though I don't understand why). But thank you very much anyway.

I modified the structure/writing style of my .cds file.

Before:

service My_SRV { entity MoeSet as projection on TestSet; } entity TestSet { key testKey : String(64); inputData : String(100); memo: String(100); outputData: String(100); }

After:

service My_SRV { entity TestSet { key testKey : String(64); inputData : String(100); memo: String(100); outputData: String(100); } }