Symptom
When DXP 7.2 is configured with Solr 7 and your patch level is Service Pack 3 (SP3) or Fix Pack 8 (FP8) or higher, the following error is thrown in the console when starting DXP and the Solr 7 connector cannot be activated:
2020-09-14 14:50:05.923 ERROR [Framework Event Dispatcher: Equinox Container: e4150f8c-c648-4638-887e-85d8a445b425][Framework:93] FrameworkEvent ERROR
org.osgi.framework.BundleException: Could not resolve module: com.liferay.portal.search.solr7.impl [1136]_ Unresolved requirement: Import-Package: com.liferay.portal.search.engine.adapter.document; version="[2.1.0,2.2.0)"_ [Sanitized]
at org.eclipse.osgi.container.Module.start(Module.java:444)
at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:1682)
at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:1662)
at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.doContainerStartLevel(ModuleContainer.java:1624)
at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1555)
at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:340)
Resolution
You have to install Liferay's Solr 7 connector version 2.1.0 or higher from Marketplace.