Unable to save settings due to invalid Color Scheme settings

Problem

IDE shows a lot of Notifications like Failed to save settings. Please restart DataGrip., or Please restart IntelliJ IDEA.

Cause

Check the IDE log file, which contains the following message:

WARN - #c.i.o.c.i.s.StoreUtil - Save settings failed
java.lang.RuntimeException: Cannot save scheme colors/_@user_Rider Melon Dark
Caused by: java.lang.IllegalStateException: @NotNull method com/intellij/openapi/editor/colors/impl/AbstractColorsScheme.getName must not return null
	at com.intellij.openapi.editor.colors.impl.AbstractColorsScheme.$$$reportNull$$$0(AbstractColorsScheme.java)
	at com.intellij.openapi.editor.colors.impl.AbstractColorsScheme.getName(AbstractColorsScheme.java:148)
	at com.intellij.openapi.editor.colors.impl.AbstractColorsScheme.writeExternal(AbstractColorsScheme.java:544)
	at com.intellij.openapi.editor.colors.impl.AbstractColorsScheme.writeScheme(AbstractColorsScheme.java:976)

or similar to

2024-10-29 16:47:12,570 [ 597] WARN - #c.i.i.u.UIThemeProvider - accent2=#FF98002 has # prefix but cannot be parsed as color [Plugin: com.mallowigi.idea]
com.intellij.diagnostic.PluginException: accent2=#FF98002 has # prefix but cannot be parsed as color [Plugin: com.mallowigi.idea]
at com.intellij.ide.ui.UIThemeProvider$createTheme$1.invoke(UIThemeProvider.kt:93)

Some invalid editor color scheme causes this. Usually, you install one theme plugin, but then you uninstall or disable that, and then the IDE can't find the color scheme anymore.

Resolution

Via the menu "File | Settings | Editor | Color Scheme ", select a valid color scheme. Then this problem will be fixed.

Ref: Unable to save settings