Why pluginUntilBuild is mandatory

There is no hard rule whether to specify untilBuild or leave it "open". It basically depends on your chosen strategy of targeting a range of platform versions, e.g. by using dedicated branches and limiting until-build for each platform accordingly.

Otherwise, using Plugin Verifier allows checking for problems (also locally) https://plugins.jetbrains.com/docs/intellij/api-changes-list.html#verifying-compatibility and can be run against any later released version(s).

The probability of problems or incompatibilities largely depends on the specific API a plugin is using, so there's no general advice on which strategy to use.

If I don't specify untilBuild I can't install it too Intellije IDEA, it says untilBuild is not specified. I created plugin using template in GitHub

Please show final plugin.xml and note your exact IDE version you try to install into

It is almost empty

<idea-plugin>
    <id>com.***</id>
    <name>plugin name</name>
    <vendor>***</vendor>

    <depends>com.intellij.modules.platform</depends>

    <extensions defaultExtensionNs="com.intellij">
        <psi.referenceContributor implementation="com.*.contributor.XmlPsiReferenceContributor" language="XML" id="my" order="first"/>
        <gotoTargetRendererProvider implementation="com.*.contributor.XmlGotoTargetRendererProvider" order="first"/>
    </extensions>
</idea-plugin>

There is no since-build which mandatory. Please see https://plugins.jetbrains.com/docs/intellij/gradle-guide.html#patching-the-plugin-configuration-file on how to set values.

It works, thank you, I've put the version into plugin.xml, and removed code with method patchPluginXml from file build.gradle.kts 

patchPluginXml {
    version(properties("pluginVersion"))
    sinceBuild(properties("pluginSinceBuild"))
    untilBuild(properties("pluginUntilBuild"))

if I remove only untilBuild(properties("pluginUntilBuild")) line, without mentions sinceBuild in plugin.xml, then I install the plugin, IDEA says untilBuild not mentioned and denies installing the plugin. Is that possible to mention only sinceBuild version in gradle.properties file. What should I do in order to mention just pluginSinceBuild in properties?

pluginVersion = 0.0.2
pluginSinceBuild = 183

build.gradle.kts file 

import io.gitlab.arturbosch.detekt.Detekt
import org.jetbrains.changelog.closure
import org.jetbrains.changelog.markdownToHTML
import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

fun properties(key: String) = project.findProperty(key).toString()
System.setProperty("user.dir", projectDir.toString())

plugins {
    // Java support
    id("java")
    // Kotlin support
    id("org.jetbrains.kotlin.jvm") version "1.4.31"
    // gradle-intellij-plugin - read more: https://github.com/JetBrains/gradle-intellij-plugin
    id("org.jetbrains.intellij") version "0.7.2"
    // gradle-changelog-plugin - read more: https://github.com/JetBrains/gradle-changelog-plugin
    id("org.jetbrains.changelog") version "1.1.2"
    // detekt linter - read more: https://detekt.github.io/detekt/gradle.html
    id("io.gitlab.arturbosch.detekt") version "1.15.0"
    // ktlint linter - read more: https://github.com/JLLeitschuh/ktlint-gradle
    id("org.jlleitschuh.gradle.ktlint") version "10.0.0"
}

group = properties("pluginGroup")
version = properties("pluginVersion")

// Configure project's dependencies
repositories {
    mavenCentral()
    jcenter()
}
dependencies {
    detektPlugins("io.gitlab.arturbosch.detekt:detekt-formatting:1.15.0")
}

// Configure gradle-intellij-plugin plugin.
// Read more: https://github.com/JetBrains/gradle-intellij-plugin
intellij {
    pluginName = properties("pluginName")
    version = properties("platformVersion")
    type = properties("platformType")
    downloadSources = properties("platformDownloadSources").toBoolean()
//    updateSinceUntilBuild = true

    // Plugin Dependencies. Uses `platformPlugins` property from the gradle.properties file.
    setPlugins(*properties("platformPlugins").split(',').map(String::trim).filter(String::isNotEmpty).toTypedArray())
}

// Configure gradle-changelog-plugin plugin.
// Read more: https://github.com/JetBrains/gradle-changelog-plugin
changelog {
    version = properties("pluginVersion")
    groups = emptyList()
}

// Configure detekt plugin.
// Read more: https://detekt.github.io/detekt/kotlindsl.html
detekt {
    config = files("./detekt-config.yml")
    buildUponDefaultConfig = true

    reports {
        html.enabled = false
        xml.enabled = false
        txt.enabled = false
    }
}

tasks {
    // Set the compatibility versions to 1.8
    withType<JavaCompile> {
        sourceCompatibility = "1.8"
        targetCompatibility = "1.8"
    }
    withType<KotlinCompile> {
        kotlinOptions.jvmTarget = "1.8"
    }

    withType<Detekt> {
        jvmTarget = "1.8"
    }

    patchPluginXml {
        version(properties("pluginVersion"))
        sinceBuild("202.*")
//        untilBuild(properties("pluginUntilBuild"))

        pluginDescription(
            closure {
                File("./README.md").readText().lines().run {
                    val start = "<!-- Plugin description -->"
                    val end = "<!-- Plugin description end -->"

                    if (!containsAll(listOf(start, end))) {
                        throw GradleException("Plugin description section not found in README.md:\n$start ... $end")
                    }
                    subList(indexOf(start) + 1, indexOf(end))
                }.joinToString("\n").run { markdownToHTML(this) }
            }
        )

        // Get the latest available change notes from the changelog file
        changeNotes(
            closure {
                changelog.getLatest().toHTML()
            }
        )
    }

//    runPluginVerifier {
//        ideVersions(properties("pluginVerifierIdeVersions"))
//    }

    publishPlugin {
        dependsOn("patchChangelog")
        token(System.getenv("PUBLISH_TOKEN"))
        // pluginVersion is based on the SemVer (https://semver.org) and supports pre-release labels, like 2.1.7-alpha.3
        // Specify pre-release label to publish the plugin in a custom Release Channel automatically. Read more:
        // https://plugins.jetbrains.com/docs/intellij/deployment.html#specifying-a-release-channel
        channels(properties("pluginVersion").split('-').getOrElse(1) { "default" }.split('.').first())
    }
}

plugin.xml 

<idea-plugin>
    <id>com.***</id>
    <name>plugin name</name>
    <vendor>***</vendor>

    <depends>com.intellij.modules.platform</depends>

    <extensions defaultExtensionNs="com.intellij">
        <psi.referenceContributor implementation="com.*.contributor.XmlPsiReferenceContributor" language="XML" id="my" order="first"/>
        <gotoTargetRendererProvider implementation="com.*.contributor.XmlGotoTargetRendererProvider" order="first"/>
    </extensions>
</idea-plugin>

If comment untilBuild(properties("pluginUntilBuild")) when intall the plugin IDEA shows 

The plugin is not compatible with the current version of the IDE, because it requires  build 202.* or older but the current build is IU-211.6693.111

What to do in order to mention version only in build.gradle.kts

Sorry, I'm a bit lost of what you have now and want to achieve. You are setting this value "202.*" in your Gradle build script explicitly, so obviously it cannot be installed into earlier versions like 211.6693.111.

I suggest to remove both since/until-build attributes from your plugin.xml _completely_ and set them as you wish from build.gradle patchPluginXml task. All the variants are fully described in docs mentioned above (https://plugins.jetbrains.com/docs/intellij/gradle-guide.html#patching-the-plugin-configuration-file).

The patching DSL generates both, the required `since-build` and the optional `until-build` attribute in plugin.xml regardless, even when the latter is not specified in the `patchPluginXml` in build.gradle. IMHO this is a source of confusion (confused me at least).

The solution is to not use patching DSL at all (`intellij.updateSinceUntilBuild = false`) and leave only `idea-version` tag in plugin.xml.

When I set `until-build` to `null`, I see that it is produced in the XML. However, it is not produced when I set `until-build` to an empty string.

The `intellij-platform-gradle-plugin` repo has lots of github workflow bits that depend on these properties being set. This is getting painfully time consuming to fix/workaround.

Please see the linked page above https://plugins.jetbrains.com/docs/intellij/configuring-plugin-project.html#patching-the-plugin-configuration-file, it documents this topic in great detail.