diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index ad6937558..d7ced0647 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -350,6 +350,8 @@ android.applicationVariants.all {
             }
         }
 
+        from(File(magiskDir, "boot_common.sh"))
+        from(File(magiskDir, "post-fs-data.sh"))
         from(File(magiskDir, "service.sh"))
 
         from(File(rootDir, "LICENSE"))
diff --git a/app/magisk/boot_common.sh b/app/magisk/boot_common.sh
new file mode 100644
index 000000000..654986427
--- /dev/null
+++ b/app/magisk/boot_common.sh
@@ -0,0 +1,34 @@
+# source "${0%/*}/boot_common.sh" <log file>
+
+exec >"${1}" 2>&1
+
+mod_dir=${0%/*}
+
+header() {
+    echo "----- ${*} -----"
+}
+
+module_prop() {
+    grep "^${1}=" "${mod_dir}/module.prop" | cut -d= -f2
+}
+
+run_cli_apk() {
+    CLASSPATH="${cli_apk}" app_process / "${@}" &
+    pid=${!}
+    wait "${pid}"
+    echo "Exit status: ${?}"
+    echo "Logcat:"
+    logcat -d --pid "${pid}"
+}
+
+app_id=$(module_prop id)
+app_version=$(module_prop version)
+cli_apk=$(echo "${mod_dir}"/system/priv-app/"${app_id}"/app-*.apk)
+
+header Environment
+echo "Timestamp: $(date)"
+echo "Script: ${0}"
+echo "App ID: ${app_id}"
+echo "App version: ${app_version}"
+echo "CLI APK: ${cli_apk}"
+echo "UID/GID/Context: $(id)"
diff --git a/app/magisk/post-fs-data.sh b/app/magisk/post-fs-data.sh
new file mode 100644
index 000000000..7669f36b8
--- /dev/null
+++ b/app/magisk/post-fs-data.sh
@@ -0,0 +1,13 @@
+# On some devices, upgrading BCR seems to cause some old state to unexpectedly
+# linger around, causing BCR to crash with an obscure error about the theme not
+# being derived from Theme.AppCompat.
+
+source "${0%/*}/boot_common.sh" /data/local/tmp/bcr_clear_package_manager_caches.log
+
+header Timestamps
+ls -lZ "${cli_apk}"
+ls -lZ "${cli_apk#"${mod_dir}"}"
+find /data/system/package_cache -name "${app_id}-*" -exec ls -lZ {} \+
+
+header Clear package manager caches
+run_cli_apk com.chiller3.bcr.standalone.ClearPackageManagerCachesKt
diff --git a/app/magisk/service.sh b/app/magisk/service.sh
index d30387870..b6ea49200 100644
--- a/app/magisk/service.sh
+++ b/app/magisk/service.sh
@@ -5,38 +5,10 @@
 # to alter the flags. This command blocks for an arbitrary amount of time
 # because it needs to wait until the primary user unlocks the device.
 
-exec >/data/local/tmp/bcr_remove_hard_restrictions.log 2>&1
-
-mod_dir=${0%/*}
-
-header() {
-    echo "----- ${*} -----"
-}
-
-module_prop() {
-    grep "^${1}=" "${mod_dir}/module.prop" | cut -d= -f2
-}
-
-app_id=$(module_prop id)
-app_version=$(module_prop version)
-
-header Environment
-echo "Timestamp: $(date)"
-echo "Args: ${0} ${*}"
-echo "Version: ${app_version}"
-echo "UID/GID/Context: $(id)"
+source "${0%/*}/boot_common.sh" /data/local/tmp/bcr_remove_hard_restrictions.log
 
 header Remove hard restrictions
-CLASSPATH=$(find "${mod_dir}"/system/priv-app/"${app_id}" -name '*.apk') \
-    app_process \
-    / \
-    com.chiller3.bcr.standalone.RemoveHardRestrictionsKt &
-pid=${!}
-wait "${pid}"
-echo "Exit status: ${?}"
-
-header Logcat
-logcat -d --pid "${pid}"
+run_cli_apk com.chiller3.bcr.standalone.RemoveHardRestrictionsKt
 
 header Package state
 dumpsys package "${app_id}"
diff --git a/app/src/main/java/com/chiller3/bcr/standalone/ClearPackageManagerCaches.kt b/app/src/main/java/com/chiller3/bcr/standalone/ClearPackageManagerCaches.kt
new file mode 100644
index 000000000..672d1a973
--- /dev/null
+++ b/app/src/main/java/com/chiller3/bcr/standalone/ClearPackageManagerCaches.kt
@@ -0,0 +1,95 @@
+@file:Suppress("SameParameterValue")
+
+package com.chiller3.bcr.standalone
+
+import com.chiller3.bcr.BuildConfig
+import java.nio.file.Path
+import java.nio.file.Paths
+import kotlin.io.path.ExperimentalPathApi
+import kotlin.io.path.deleteIfExists
+import kotlin.io.path.isRegularFile
+import kotlin.io.path.readBytes
+import kotlin.io.path.walk
+import kotlin.system.exitProcess
+
+private val PACKAGE_CACHE_DIR = Paths.get("/data/system/package_cache")
+
+private var dryRun = false
+
+private fun delete(path: Path) {
+    if (dryRun) {
+        println("Would have deleted: $path")
+    } else {
+        println("Deleting: $path")
+        path.deleteIfExists()
+    }
+}
+
+private fun ByteArray.indexOfSubarray(needle: ByteArray, start: Int = 0): Int {
+    require(start >= 0) { "start must be non-negative" }
+
+    if (needle.isEmpty()) {
+        return 0
+    }
+
+    outer@ for (i in 0 until size - needle.size + 1) {
+        for (j in needle.indices) {
+            if (this[i + j] != needle[j]) {
+                continue@outer
+            }
+        }
+        return i
+    }
+
+    return -1
+}
+
+@OptIn(ExperimentalPathApi::class)
+private fun clearPackageManagerCache(appId: String): Boolean {
+    // The current implementation of the package cache uses PackageImpl.writeToParcel(), which
+    // serializes the cache entry to the file as a Parcel. The current Parcel implementation stores
+    // string values as null-terminated little-endian UTF-16. One of the string values stored is
+    // manifestPackageName, which we can match on.
+    //
+    // This is a unique enough search that there should never be a false positive, but even if there
+    // is, the package manager will just repopulate the cache.
+    val needle = "\u0000$appId\u0000".toByteArray(Charsets.UTF_16LE)
+    var ret = true
+
+    for (path in PACKAGE_CACHE_DIR.walk()) {
+        if (!path.isRegularFile()) {
+            continue
+        }
+
+        try {
+            // Not the most efficient, but these are tiny files that Android is later going to read
+            // entirely into memory anyway
+            if (path.readBytes().indexOfSubarray(needle) >= 0) {
+                delete(path)
+            }
+        } catch (e: Exception) {
+            e.printStackTrace()
+            ret = false
+        }
+    }
+
+    return ret
+}
+
+private fun mainInternal() {
+    clearPackageManagerCache(BuildConfig.APPLICATION_ID)
+}
+
+fun main(args: Array<String>) {
+    if ("--dry-run" in args) {
+        dryRun = true
+    }
+
+    try {
+        mainInternal()
+    } catch (e: Exception) {
+        System.err.println("Failed to clear caches")
+        e.printStackTrace()
+        exitProcess(1)
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/chiller3/bcr/standalone/RemoveHardRestrictions.kt b/app/src/main/java/com/chiller3/bcr/standalone/RemoveHardRestrictions.kt
index 05102befc..c8caa4503 100644
--- a/app/src/main/java/com/chiller3/bcr/standalone/RemoveHardRestrictions.kt
+++ b/app/src/main/java/com/chiller3/bcr/standalone/RemoveHardRestrictions.kt
@@ -272,7 +272,7 @@ private fun waitForLogin(userId: Int) {
         "User $userId did not unlock the device after $IS_USER_UNLOCKED_ATTEMPTS attempts")
 }
 
-fun mainInternal() {
+private fun mainInternal() {
     if (Build.VERSION.SDK_INT == Build.VERSION_CODES.P) {
         println("Android 9 does not have hard-restricted permissions")
         return