KB-2340 Data server fails to start because localhost lookup fails

pauline.delacruz — Tue, 03 Jun 2025 18:34:32 GMT

Current Revision posted to Appian Knowledge Base by pauline.delacruz on 6/3/2025 6:34:32 PM

Symptoms

When attempting to start the Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Check the hosts file of the server to ensure that there is an entry for the FQDN of the Appian instance that resolves to the IP address of the server (the same FQDN used in appian-topology.xml). If Appian is being hosted locally on the server, "localhost" can be used, but it must explicitly resolve to 127.0.0.1 in the host file.

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the hosts file to mitigate confusion and prevent errors of this nature. Additionally, please make sure that the content of appian-topology.xml is exactly the same in <APPIAN_HOME>/conf/, <APPIAN_HOME>/data-server/conf/, <APPIAN_HOME>/search-server/conf/ on each server and between all three nodes in the case of an HA installation.

Affected Versions

This article applies to all non-containerized self-managed versions of Appian.

Last Reviewed: June 2025

Tags: IP address, data server, infrastructure, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

Yiyi Tao — Tue, 03 Jun 2025 18:30:36 GMT

Revision 10 posted to Appian Knowledge Base by Yiyi Tao on 6/3/2025 6:30:36 PM

Symptoms

When attempting to start the Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Affected Versions

This article applies to all non-containerized self-managed versions of Appian.

Last Reviewed: June 2025

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

Yiyi Tao — Tue, 03 Jun 2025 18:30:36 GMT

Revision 11 posted to Appian Knowledge Base by Yiyi Tao on 6/3/2025 6:30:36 PM

Symptoms

When attempting to start the Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Affected Versions

This article applies to all non-containerized self-managed versions of Appian.

Last Reviewed: June 2025

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

joe.dubravec — Tue, 04 Feb 2025 20:13:41 GMT

Revision 9 posted to Appian Knowledge Base by joe.dubravec on 2/4/2025 8:13:41 PM

Symptoms

When attempting to start the Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the hosts file to mitigate confusion and prevent errors of this nature. Additionally, please make sure that the content of appian-topology.xml is exactly the same in all three locations on the server and between all three nodes in the case of an HA installation.

Affected Versions

This article applies to all self-managed versions of Appian.

Last Reviewed: February 2025

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

pauline.delacruz — Tue, 04 Feb 2025 18:09:20 GMT

Revision 8 posted to Appian Knowledge Base by pauline.delacruz on 2/4/2025 6:09:20 PM

Symptoms

When attempting to start the Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the hosts file to mitigate confusion and prevent errors of this nature.

Affected Versions

This article applies to all self-managed versions of Appian.

Last Reviewed: February 2025

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

pauline.delacruz — Tue, 04 Feb 2025 18:08:29 GMT

Revision 7 posted to Appian Knowledge Base by pauline.delacruz on 2/4/2025 6:08:29 PM

Symptoms

When attempting to start Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the hosts file to mitigate confusion and prevent errors of this nature.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: February 2025

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

pauline.delacruz — Tue, 04 Feb 2025 18:07:31 GMT

Revision 6 posted to Appian Knowledge Base by pauline.delacruz on 2/4/2025 6:07:31 PM

Symptoms

When attempting to start Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Check the host file of the server to ensure that there is an entry for the FQDN of the Appian instance that resolves to the IP address of the server (the same FQDN used in appian-topology.xml) . If Appian is being hosted locally on the server, "localhost" can be used, but it must explicitly resolve to 127.0.0.1 in the host file.

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the host file to mitigate confusion and prevent errors of this nature.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: February 2025

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

joe.dubravec — Tue, 04 Feb 2025 17:56:20 GMT

Revision 5 posted to Appian Knowledge Base by joe.dubravec on 2/4/2025 5:56:20 PM

Symptoms

When attempting to start Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the necessary ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the host file to mitigate confusion and prevent errors of this nature.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: Month YYYY

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

joe.dubravec — Tue, 04 Feb 2025 17:55:49 GMT

Revision 4 posted to Appian Knowledge Base by joe.dubravec on 2/4/2025 5:55:49 PM

Symptoms

When attempting to start Appian Data Server (ADS), the startup fails due to the following errors in watchdog.log:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

ADS is unable to establish a connection to the ADS-established ports because "localhost" is not resolvable to the IP address of the server (ex: 127.0.0.1), which causes the lookup and connection to fail.

Action

Note that Appian recommends using FQDNs instead of "localhost" in appian-topology.xml and the host file to mitigate confusion and prevent errors of this nature.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: Month YYYY

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

joe.dubravec — Tue, 04 Feb 2025 17:48:21 GMT

Revision 3 posted to Appian Knowledge Base by joe.dubravec on 2/4/2025 5:48:21 PM

Symptoms

When attempting to start Appian Data Server (ADS), the startup fails due to the following errors in ```watchdog.log```:

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

Action

Check the host file of the server to ensure that there is an entry for the FQDN of the Appian instance that resolves to the IP address of the server (the same FQDN used in `appian-topology.xml`) . If Appian is being hosted locally on the server, "localhost" can be used, but it must explicitly resolve to 127.0.0.1 in the host file.

Note that Appian recommends using FQDNs instead of "localhost" in `appian-topology.xml` and the host file to mitigate confusion and prevent errors of this nature.

Affected Versions

This section includes any relevant version information for Appian or other third/party configurations. Some examples of valid affected versions are as follows:

This article applies to all versions of Appian.

Last Reviewed: Month YYYY

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

joe.dubravec — Tue, 04 Feb 2025 17:47:44 GMT

Revision 2 posted to Appian Knowledge Base by joe.dubravec on 2/4/2025 5:47:44 PM

Symptoms

When attempting to start Appian Data Server (ADS), the startup fails due to the following errors in

watchdog.log

com.appian.data.server.UnrecoverableError: Lost WebSocket connection with localhost:5410. The target Go process exited abnormally. Check for earlier errors (e.g. Go startup errors).

The following error may also appear:

dial tcp: lookup localhost: Try again

Cause

Action

Note that Appian recommends using FQDNs instead of "localhost" in `appian-topology.xml` and the host file to mitigate confusion and prevent errors of this nature.

Affected Versions

This section includes any relevant version information for Appian or other third/party configurations. Some examples of valid affected versions are as follows:

This article applies to all versions of Appian.

Last Reviewed: Month YYYY

Tags: IP address, data server, network

[SUPP-820 Draft] KB-XXXX Data server fails to start because localhost lookup fails

joe.dubravec — Mon, 30 Dec 2024 20:13:52 GMT

Revision 1 posted to Appian Knowledge Base by joe.dubravec on 12/30/2024 8:13:52 PM

Symptoms

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Cause

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The cause is concise and does not disclose more information than absolutely necessary.
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This issue has been reported to the Appian Product Team. The reference number for this issue is AN-XXXXX.
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This issue has been hotfixed via AN-XXXXX in Appian X.X.
This issue has been hotfixed via AN-XXXXX in Appian X.X to X.X.
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When logging a product defect, ensure you use the known issues tag as well as the open issues or fixed issues tag, depending if the issue is fixed or not.

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Action

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Apply the latest hotfix to your Appian installation.
Upgrade to the latest version of Appian.
Apply the latest hotfix to your Appian installation or upgrade to the latest version of Appian.

If there is a product issue with Engineering that is open and a workaround for that issue exists, include it in the Action section until the fix is available. After the fix is made available, use that as a workaround instead.

Otherwise, the content in this section should wholly solve a customer’s issue without producing any undesirable side effects. If there is at least one valid action that doesn’t cause undesirable side effects, all other actions with negative side effects should go in the Workaround section.

If there is no action or workaround that resolves the issue, use the following language:

There is no action or workaround currently available for this issue. If you are facing this issue, please open a support case with Appian.

Workaround

This section is optional and should only be used as an alternative action if there is a massive technical debt associated with performing the action in the above section for customers (such as upgrading). It can also be used if there is a solution to the issue in the article but is more inconvenient to implement or it causes other undesirable behavior and wouldn’t warrant being an action.

Affected Versions

This section includes any relevant version information for Appian or other third/party configurations. Some examples of valid affected versions are as follows:

This article applies to all versions of Appian.
This article applies to all self-managed versions of Appian.
This article applies to all versions of Appian Cloud.
This article applies to Appian 7.11 and later.
This article applies to Appian 16.2 and earlier.
This article applies to Appian 7.11 and 16.1.
This article applies to Appian 16.1, 16.2, and 16.3.
This article applies to self-managed Appian 19.3 and earlier.
This article applies to all versions of Appian from Appian 7.10 to Appian 16.2.
This article applies to all versions of Appian using JBoss EAP 6.4.9 as an application server and Internet Explorer 9 as a web browser.

Last Reviewed: Month YYYY