Settings Sync/Backup and Sync couldn't be enabled or displays the error in the settings window

Since 2024.3 release, Settings Sync feature was renamed to Backup and Sync

Problem

• Settings Sync couldn't be enabled in the Settings | Settings Sync window, or it disables itself with the error displayed in the settings window;
• the displayed error could be, for example, Checkout conflict with files, Not a DIRC file, etc.

• the error is also reported in the IDE logs, for example:

java.lang.AssertionError: Checkout conflict with files: 
.metainfo/plugins.json
	at com.intellij.openapi.diagnostic.DefaultLogger.error(DefaultLogger.java:54)
	at com.intellij.openapi.diagnostic.Logger.error(Logger.java:429)
	at com.intellij.util.concurrency.SchedulingWrapper$MyScheduledFutureTask.setException(SchedulingWrapper.java:288)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:269)
	at com.intellij.util.concurrency.SchedulingWrapper$MyScheduledFutureTask.run(SchedulingWrapper.java:272)
	at com.intellij.util.concurrency.BoundedTaskExecutor.doRun(BoundedTaskExecutor.java:248)
	at com.intellij.util.concurrency.BoundedTaskExecutor.access$200(BoundedTaskExecutor.java:28)
	at com.intellij.util.concurrency.BoundedTaskExecutor$1.executeFirstTaskAndHelpQueue(BoundedTaskExecutor.java:221)
	at com.intellij.util.ConcurrencyUtil.runUnderThreadName(ConcurrencyUtil.java:228)
	at com.intellij.util.concurrency.BoundedTaskExecutor$1.run(BoundedTaskExecutor.java:210)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:702)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:699)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:699)
	at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: org.eclipse.jgit.api.errors.CheckoutConflictException: Checkout conflict with files: 
.metainfo/plugins.json
	at org.eclipse.jgit.api.CheckoutCommand.call(CheckoutCommand.java:252)
	at com.intellij.settingsSync.GitSettingsLog.applyState(GitSettingsLog.kt:143)
	at com.intellij.settingsSync.GitSettingsLog.copyExistingSettings(GitSettingsLog.kt:102)
	at com.intellij.settingsSync.GitSettingsLog.logExistingSettings(GitSettingsLog.kt:85)
	at com.intellij.settingsSync.SettingsSyncBridge.applyInitialChanges(SettingsSyncBridge.kt:86)
	at com.intellij.settingsSync.SettingsSyncBridge.initialize$intellij_settingsSync(SettingsSyncBridge.kt:72)
	at com.intellij.settingsSync.SettingsSynchronizer.initializeSyncing$lambda$1(SettingsSynchronizer.kt:72)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	... 13 more
Caused by: org.eclipse.jgit.errors.CheckoutConflictException: Checkout conflict with files: 
.metainfo/plugins.json
	at org.eclipse.jgit.dircache.DirCacheCheckout.doCheckout(DirCacheCheckout.java:500)
	at org.eclipse.jgit.dircache.DirCacheCheckout.checkout(DirCacheCheckout.java:465)
	at org.eclipse.jgit.api.CheckoutCommand.call(CheckoutCommand.java:248)
	... 21 more

Resolution

Perform the following steps to reset the Settings Sync local repository:

• close the IDE;
• open the IDE configuration directory;
• remove the settingsSync folder inside;
• open the IDE and enable Settings Sync again.

The IDE settings are not affected by the removed settingsSync folder.