We are running Apache NiFi 2.4 (NifiKop Helm chart) in a clustered environment.
When NiFi attempts to start up and synchronize with Bitbucket Cloud Registry Client, the application fails to fully initialize.
2025-09-04 13:57:41,246 INFO [Framework Task Thread-27] o.a.n.a.b.BitbucketFlowRegistryClient BitbucketFlowRegistryClient[id=XXXXXX] Initializing repository client
When this occurs, the Controller Settings → Registry Clients page cannot load, and NiFi remains blocked.
If we disable the Bitbucket registry (by modifying the registry client URL so it cannot connect), NiFi starts consistently without issue.
We need guidance on:
Whether this is a known issue in NiFi 2.4’s Bitbucket Flow Registry Client.
Whether there is a configuration option to force HTTP/1.1 or limit HTTP/2 concurrency for registry communications. (Not sure if this is the case)
Whether there is a supported workaround to prevent registry client initialization from blocking NiFi startup when many versioned process groups are present.
Logs when NiFi Starts Successfully (but with Errors)
Example log with “too many concurrent streams” during startup:
at org.apache.nifi.web.client.StandardWebClientService$StandardHttpRequestBodySpec.getResponse(StandardWebClientService.java:366)
at org.apache.nifi.web.client.StandardWebClientService$StandardHttpRequestBodySpec.retrieve(StandardWebClientService.java:349)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at org.apache.nifi.controller.service.StandardControllerServiceInvocationHandler.invoke(StandardControllerServiceInvocationHandler.java:251)
at org.apache.nifi.controller.service.StandardControllerServiceInvocationHandler$ProxiedReturnObjectInvocationHandler.invoke(StandardControllerServiceInvocationHandler.java:237)
at jdk.proxy26/jdk.proxy26.$Proxy234.retrieve(Unknown Source)
at org.apache.nifi.atlassian.bitbucket.BitbucketRepositoryClient.getPagedResponseValues(BitbucketRepositoryClient.java:373)
at org.apache.nifi.atlassian.bitbucket.BitbucketRepositoryClient.getListCommits(BitbucketRepositoryClient.java:362)
at org.apache.nifi.atlassian.bitbucket.BitbucketRepositoryClient.getLatestCommit(BitbucketRepositoryClient.java:403)
at org.apache.nifi.atlassian.bitbucket.BitbucketRepositoryClient.getContentFromBranch(BitbucketRepositoryClient.java:244)
at org.apache.nifi.registry.flow.git.AbstractGitFlowRegistryClient.getSnapshot(AbstractGitFlowRegistryClient.java:491)
at org.apache.nifi.registry.flow.git.AbstractGitFlowRegistryClient.getFlow(AbstractGitFlowRegistryClient.java:279)
at org.apache.nifi.registry.flow.StandardFlowRegistryClientNode.lambda$getFlow$6(StandardFlowRegistryClientNode.java:231)
at org.apache.nifi.registry.flow.StandardFlowRegistryClientNode.execute(StandardFlowRegistryClientNode.java:314)
at org.apache.nifi.registry.flow.StandardFlowRegistryClientNode.getFlow(StandardFlowRegistryClientNode.java:231)
at org.apache.nifi.groups.StandardProcessGroup.synchronizeWithFlowRegistry(StandardProcessGroup.java:3769)
at org.apache.nifi.groups.StandardProcessGroup.lambda$setVersionControlInformation$27(StandardProcessGroup.java:3575)
at org.apache.nifi.controller.scheduling.StandardProcessScheduler.lambda$wrapTask$1(StandardProcessScheduler.java:177)
at java.base/java.lang.VirtualThread.run(VirtualThread.java:329)
Caused by: java.io.IOException: too many concurrent streams
at java.net.http/jdk.internal.net.http.HttpClientImpl.send(HttpClientImpl.java:967)
at java.net.http/jdk.internal.net.http.HttpClientFacade.send(HttpClientFacade.java:133)
at org.apache.nifi.web.client.StandardWebClientService$StandardHttpRequestBodySpec.getResponse(StandardWebClientService.java:364)
... 19 common frames omitted
Caused by: java.io.IOException: too many concurrent streams
at java.net.http/jdk.internal.net.http.Http2Connection.reserveStream0(Http2Connection.java:616)
at java.net.http/jdk.internal.net.http.Http2Connection.reserveStream(Http2Connection.java:583)
at java.net.http/jdk.internal.net.http.Http2ClientImpl.getConnectionFor(Http2ClientImpl.java:109)
at java.net.http/jdk.internal.net.http.ExchangeImpl.get(ExchangeImpl.java:94)
at java.net.http/jdk.internal.net.http.Exchange.establishExchange(Exchange.java:391)
at java.net.http/jdk.internal.net.http.Exchange.responseAsyncImpl0(Exchange.java:584)
at java.net.http/jdk.internal.net.http.Exchange.responseAsyncImpl(Exchange.java:428)
at java.net.http/jdk.internal.net.http.Exchange.responseAsync(Exchange.java:420)
at java.net.http/jdk.internal.net.http.MultiExchange.responseAsyncImpl(MultiExchange.java:414)
at java.net.http/jdk.internal.net.http.MultiExchange.lambda$responseAsync0$2(MultiExchange.java:347)
at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1150)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1773)
at java.net.http/jdk.internal.net.http.HttpClientImpl$DelegatingExecutor.execute(HttpClientImpl.java:177)
at java.base/java.util.concurrent.CompletableFuture.completeAsync(CompletableFuture.java:2719)
at java.net.http/jdk.internal.net.http.MultiExchange.responseAsync(MultiExchange.java:300)
at java.net.http/jdk.internal.net.http.HttpClientImpl.sendAsync(HttpClientImpl.java:1050)
at java.net.http/jdk.internal.net.http.HttpClientImpl.send(HttpClientImpl.java:931)
... 21 common frames omitted
