Summary: This article explains why a Synthetic‑enabled ActiveGate may show a 'shutting down' status, and so not run any monitors, and provides troubleshooting steps covering version mismatches, security software interference, Chromium issues, missing libraries, and OS‑specific causes.
- Synthetic Engine Status
- Troubleshooting
- ActiveGate and Synthetic Module mismatch
- Security software
- Chromium
- Log Messages
- Windows Machines
- What's Next
Synthetic Engine Status
When checking the health of a Synthetic-enabled ActiveGate, the Deployment Status > ActiveGates page is one of the first places to look. This page provides helpful information on the current status of the ActiveGate, the enabled modules, the versions in use, and whether it is running.
This article contains troubleshooting steps for when an ActiveGate with Synthetic enabled is running, but the Synthetic Engine Status shows as shutting down, as seen in Deployment Status > ActiveGates.
This situation occurs when there is a problem starting the Synthetic module. If the self-diagnostic test fails, the Synthetic module will restart in an attempt to run again. If the restart does not resolve the startup problem, the Synthetic module becomes stuck in a loop of going offline, running the self-diagnostic test, shutting down and going offline again.
Troubleshooting
ActiveGate and Synthetic Module mismatch
Check if the Synthetic and ActiveGate major versions match. In the image above, they don't.
If the major versions differ, check this article to see why the Synthetic module failed to update.
Security software
Antivirus, anti-malware and endpoint detection software can adversely affect Dynatrace Synthetic monitoring capabilities. The security software might block the Chromium browser or Dynatrace processes responsible for executing synthetic monitors, cause Synthetic-enabled ActiveGate installation and update failures, interfere with network communication, and impact the reliability of measurements.
If the machine has any security software installed or running
- Exclude the directories and processes listed here.
We recommend working with the antivirus or anti-malware software vendor to find the correct settings.
- On Windows, if the complete list has already been excluded, you may need to exclude the instance that the ActiveGate uses specifically, C:\Program Files\dynatrace\synthetic\Chrome-bin\chrome.exe is the default path.
- Disable behavioral monitoring or kernel-level hooks
Behavioral monitoring or kernel-level hooks can affect how Chrome interacts with system libraries. As a result, even excluded processes can indirectly cause access violations or heap corruption, especially during non-standard operations within Chrome, such as running Synthetic Tests.
An example of this is EDR, Endpoint Detection and Response. - If the exclusions and disabling behavioral monitoring don't change the behavior, try disabling/ removing the machine's security software to confirm if the issue occurs without it.
- For Windows machines, reboot the machine.
Chromium
Old version of Chromium
On Linux machines, a common cause of this behavior is an old version of Chromium. Dynatrace supports Chromium versions, which are no more than two versions behind the latest Dynatrace-supported version for a specific ActiveGate release. Chromium can be manually updated using the instructions here.
Chromium version shows as 80.0.0000.00
If Chromium version shows as 80.0.0000.00, then the Synthetic Module can't recognise the version.
For Linux machines
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For Ubuntu machines using snap,
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If possible, reboot the machine.
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Follow these steps to uninstall and reinstall Chromium (replace the package with the expected version from here)
sudo snap remove chromium curl --remote-name https://synthetic-packages.s3.amazonaws.com/Chromium/snap/chromium-127.0.6533.88-2923.tgz tar xzf chromium-127.0.6533.88-2923.tgz sudo snap ack chromium.assert sudo chown -R root:root /tmp/snap-private-tmp sudo snap install --devmode chromium.snap sudo chown -R dtuserag:dtuserag /tmp/snap-private-tmp -
Restart the vuc.service, or better still, reboot the machine
sudo systemctl restart vuc.service
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If SELinux is enabled, reinstall Chromium using the permissive setting.
- If the OS was recently updated by a major version, for example from RHEL 8 to RHEL 9, uninstall the ActiveGate and reinstall it.
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Check the vuc_browser.log for the following error
/opt/dynatrace/synthetic/browser: symbol lookup error:-
undefined symbol: mpg123_param2
If the full error contains/opt/dynatrace/synthetic/browser: symbol lookup error: /lib64/libopenmpt.so.0: undefined symbol: mpg123_param2Run the following command to get the latest update of the library "mpg123-libs" (version 1.32.0 or newer is required)
sudo dnf install mpg123-libs
- undefined symbol: drmSyncobjEventfd
If the full error contains/opt/dynatrace/synthetic/browser: symbol lookup error: /opt/dynatrace/synthetic/browser: undefined symbol: drmSyncobjEventfdinstall libdrm-2.4.123-2.el9.x86_64 or newer
sudo dnf install libdrm-2.4.123-2.el9.x86_64 -
undefined symbol: amdgpu_cs_ctx_stable_pstate
If the full error containssymbol lookup error: /lib64/libgallium-24.2.8.so: undefined symbol: amdgpu_cs_ctx_stable_pstate
Install the relevant library.sudo dnf upgrade mesa* libdrm* -y
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- Check the vuc_browser.debug.log for the following error
error while loading shared librariesThis means a library that Chromium depends on is not installed on the machine.
Here are a couple of examples2025-07-22T07:26:14,779Z DEBUG [v=5] [BM-gobbler-3] ChromeGobblerLogger: /opt/dynatrace/synthetic/browser: error while loading shared libraries: libcups.so.2: cannot open shared object file: No such file or directory2025-07-24T07:30:33,010Z DEBUG [v=5] [BM-gobbler-3] ChromeGobblerLogger: /opt/activegate/synthetic/browser: error while loading shared libraries: libdouble-conversion.so.3: cannot open shared object file: No such file or directory
You'll need to search the internet for the RPM containing your Linux flavor's library. For instance, if you're missing libdouble-conversion.so.3 on a Red Hat 8 machine, you would search for 'libdouble-conversion.so.3 el8'. This will provide links to suitable download pages, like https://rpmfind.net/. You can then check the name of the RPM containing this library.In this case, the library is double-conversion-3.1.5-1.el8 from the Fedora link name, but you may need to select the link to check. This is from the RPMfind link,
You can then install this on your machine using
sudo dnf install RPM_NAMEwhere RPM_NAME is the link without .rpm, so for this rpm it would be 'double-conversion-3.1.5-1.el8.x86_64'
sudo dnf install double-conversion-3.1.5-1.el8.x86_64
For all OS
See the Security software section. It is likely that an antivirus is preventing Chromium from starting up as expected.
Log Messages
Download the logs from the ActiveGate using the ActiveGate diagnostics feature; otherwise, you can check on the machine itself in /var/log/dynatrace/synthetic or %PROGRAMDATA%\dynatrace\synthetic\log.
Check the vuc-status.log for DiagnosticResultsHolder and see if any modules failed to be operational. There are four to check: MULTIPROTOCOL, HTTP, HTTP_SCRIPT, and BROWSER.
Where the module start up is successful, you'll see isOperational=true, for example
2024-09-18T01:10:53,190Z [DiagnosticResultsHolder]
browser = `DiagnosticResultsChangedEvent[moduleName=BROWSER, diagnosticCasesResult=DiagnosticCasesResult[isOperational=true, cases={BROWSER_MAIN=DiagnosticCaseDetail[isAvailable=true], BROWSER_FALLBACK=DiagnosticCaseDetail[isAvailable=true]}]]`
And where the module startup is not successful, you'll see isOperational=false, for example
2024-09-23T07:40:25,237Z [DiagnosticResultsHolder]
browser = `DiagnosticResultsChangedEvent[moduleName=BROWSER, diagnosticCasesResult=DiagnosticCasesResult[isOperational=false, cases={BROWSER_MAIN=DiagnosticCaseDetail[isAvailable=false]}]]`Depending on which modules were unable to start up, check the relevant logs for ERRORs and WARNINGS
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for HTTP Monitors, vuc-http.log, vuc-http.debug.log, and additional log files with stdout/stderr output in the executors subdirectory
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for Browser Monitors, vuc-browser.log and vuc-browser.debug.log
- Running as root without --no-sandbox is not supported
. The issue is likely related to the user running the Synthetic Engine. This should be run by dtuserag and not root. Reinstalling the ActiveGate will correct this behavior. - Failed to create directory
The issue is likely related to the location of the TEMP directory.
For Ubuntu with snap, version 20+, the temp directory path must begin with /var/tmp, for example, TEMP=/var/tmp/syn. Also, Dynatrace requires write access to /var/tmp to install Chromium snap packages. See note in docs - No usable sandbox! If you're running on Ubuntu 23.10+ or another Linux distro that has disabled unprivileged user namespaces with AppArmor
Although this message mentions Ubuntu and AppArmor, it can be seen on any Linux distro with or without AppArmor. This behavior is often seen when system hardening measures have been applied and are too restrictive.- Verify config_user_ns and max_user_namespaces kernel settings
- If AppArmor is used, confirm that AppArmor settings allow the use of unprivileged namespaces
- Running as root without --no-sandbox is not supported
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for NAM monitors, vuc-multi.log, vuc-multi.debug.log
Windows Machines
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Check if the OS is supported.
For instance, we don't support Windows 2012 (R2), and from 1.263, we found that this causes the VUC to show this shutting down status. This is due to Google stopping support for Chrome on Windows 2012 (R2) with Chrome 109. https://support.google.com/chrome/a/answer/7100626?hl=en
In Windows Server 2025, some of the tools used by the ActiveGate are deprecated. So currently this is not supported. - Check if any recent Windows updates have been applied, like this one that prevented Chrome from starting.
- Reboot the machine
- If any antivirus or anti-malware applications are running on the ActiveGate machine, see the Security software section above.
Note: Since Chromium 129, Antivirus settings that previously allowed Chromium to be installed and run have been found to be insufficient, and the complete list from here must be excluded.
For the Chrome process, you may need to be very specific and exclude the instance ActiveGate uses; C:\Program Files\dynatrace\synthetic\Chrome-bin\chrome.exe is the default path.
What's Next
If none of the previous steps resolved the issue, open a chat and provide the Support Archive from the ActiveGate with the troubleshooting steps you have already completed.
What to read next:
Synthetic Troubleshooting Map
