diff --git a/packages/sdk/src/restclient.spec.ts b/packages/sdk/src/restclient.spec.ts
index 7e2cecbf..e9ca24be 100644
--- a/packages/sdk/src/restclient.spec.ts
+++ b/packages/sdk/src/restclient.spec.ts
@@ -421,6 +421,8 @@ describe("RestClient", () => {
 
       // create new instance and compare before and after
       const existingContracts = await client.listContractAddresses();
+      const existingContractsByCode = await client.listContractsByCodeId(codeId);
+      existingContractsByCode.forEach(ctc => expect(ctc.code_id).toEqual(codeId));
 
       const result = await instantiateContract(client, pen, codeId, beneficiaryAddress, transferAmount);
       expect(result.code).toBeFalsy();
@@ -437,6 +439,11 @@ describe("RestClient", () => {
       const lastContract = diff[0];
       expect(lastContract).toEqual(myAddress);
 
+      // also by codeID list
+      const newContractsByCode = await client.listContractsByCodeId(codeId);
+      newContractsByCode.forEach(ctc => expect(ctc.code_id).toEqual(codeId));
+      expect(newContractsByCode.length).toEqual(existingContractsByCode.length + 1);
+
       // check out info
       const myInfo = await client.getContractInfo(myAddress);
       expect(myInfo.code_id).toEqual(codeId);
@@ -514,18 +521,14 @@ describe("RestClient", () => {
         // invalid query syntax throws an error
         await client.queryContractSmart(contractAddress, { nosuchkey: {} }).then(
           () => fail("shouldn't succeed"),
-          error => expect(error).toBeTruthy(),
+          error => expect(error).toMatch("Error parsing QueryMsg"),
         );
-        // TODO: debug rest server. I expect a 'Parse Error', but get
-        // Request failed with status code 500 to match 'Parse Error:'
 
         // invalid address throws an error
         await client.queryContractSmart(noContract, { verifier: {} }).then(
           () => fail("shouldn't succeed"),
-          error => expect(error).toBeTruthy(),
+          error => expect(error).toMatch("not found"),
         );
-        // TODO: debug rest server. I expect a 'not found', but get
-        // Request failed with status code 500 to match 'Parse Error:'
       });
     });
   });
diff --git a/packages/sdk/src/restclient.ts b/packages/sdk/src/restclient.ts
index 91b4647e..cd128366 100644
--- a/packages/sdk/src/restclient.ts
+++ b/packages/sdk/src/restclient.ts
@@ -1,5 +1,5 @@
 import { Encoding } from "@iov/encoding";
-import axios, { AxiosInstance } from "axios";
+import axios, { AxiosError, AxiosInstance } from "axios";
 
 import { AminoTx, CodeInfo, ContractInfo, CosmosSdkAccount, isAminoStdTx, StdTx, WasmData } from "./types";
 
@@ -128,6 +128,26 @@ function parseWasmResponse(response: WasmResponse<string>): any {
   return JSON.parse(response.result);
 }
 
+// We want to get message data from 500 errors
+// https://stackoverflow.com/questions/56577124/how-to-handle-500-error-message-with-axios
+// this should be chained to catch one error and throw a more informative one
+function parseAxios500error(err: AxiosError): never {
+  // use the error message sent from server, not default 500 msg
+  if (err.response?.data) {
+    const data = err.response.data;
+    // expect { error: string }, but otherwise dump
+    if (data.error) {
+      throw new Error(data.error);
+    } else if (typeof data === "string") {
+      throw new Error(data);
+    } else {
+      throw new Error(JSON.stringify(data));
+    }
+  } else {
+    throw err;
+  }
+}
+
 export class RestClient {
   private readonly client: AxiosInstance;
   // From https://cosmos.network/rpc/#/ICS0/post_txs
@@ -146,7 +166,7 @@ export class RestClient {
   }
 
   public async get(path: string): Promise<RestClientResponse> {
-    const { data } = await this.client.get(path);
+    const { data } = await this.client.get(path).catch(parseAxios500error);
     if (data === null) {
       throw new Error("Received null response from server");
     }
@@ -154,7 +174,7 @@ export class RestClient {
   }
 
   public async post(path: string, params: PostTxsParams): Promise<RestClientResponse> {
-    const { data } = await this.client.post(path, params);
+    const { data } = await this.client.post(path, params).catch(parseAxios500error);
     if (data === null) {
       throw new Error("Received null response from server");
     }
@@ -264,6 +284,14 @@ export class RestClient {
     return addresses || [];
   }
 
+  public async listContractsByCodeId(id: number): Promise<readonly ContractInfo[]> {
+    const path = `/wasm/code/${id}/contracts`;
+    const responseData = await this.get(path);
+    // answer may be null (go's encoding of empty array)
+    const contracts: ContractInfo[] | null = parseWasmResponse(responseData as WasmResponse);
+    return contracts || [];
+  }
+
   // throws error if no contract at this address
   public async getContractInfo(address: string): Promise<ContractInfo> {
     const path = `/wasm/contract/${address}`;
diff --git a/packages/sdk/types/restclient.d.ts b/packages/sdk/types/restclient.d.ts
index d560856f..d8a23d42 100644
--- a/packages/sdk/types/restclient.d.ts
+++ b/packages/sdk/types/restclient.d.ts
@@ -100,6 +100,7 @@ export declare class RestClient {
   listCodeInfo(): Promise<readonly CodeInfo[]>;
   getCode(id: number): Promise<Uint8Array>;
   listContractAddresses(): Promise<readonly string[]>;
+  listContractsByCodeId(id: number): Promise<readonly ContractInfo[]>;
   getContractInfo(address: string): Promise<ContractInfo>;
   getAllContractState(address: string): Promise<readonly WasmData[]>;
   queryContractRaw(address: string, key: Uint8Array): Promise<unknown | null>;