diff --git a/src/adaptor/discord/member-stats.ts b/src/adaptor/discord/member-stats.ts
index 7dadf7b2..c0bebb27 100644
--- a/src/adaptor/discord/member-stats.ts
+++ b/src/adaptor/discord/member-stats.ts
@@ -20,16 +20,16 @@ export class DiscordMemberStats
 
   async allMemberCount(): Promise<number> {
     const guild = await this.client.guilds.fetch(this.guildId);
-    if (!guild) {
-      throw new Error('guild not found');
+    if (!guild.available) {
+      throw new Error('guild unavailable');
     }
     return guild.memberCount;
   }
 
   async botMemberCount(): Promise<number> {
     const guild = await this.client.guilds.fetch(this.guildId);
-    if (!guild) {
-      throw new Error('guild not found');
+    if (!guild.available) {
+      throw new Error('guild unavailable');
     }
     const guildMemberList = await guild.members.list({ limit: 1000 });
     return guildMemberList.filter((member) => member.user.bot).size;
@@ -37,8 +37,8 @@ export class DiscordMemberStats
 
   async fetchMembersWithRole(): Promise<MemberWithRole[]> {
     const guild = await this.client.guilds.fetch(this.guildId);
-    if (!guild) {
-      throw new Error('guild not found');
+    if (!guild.available) {
+      throw new Error('guild unavailable');
     }
     const guildMemberList = await guild.members.list({ limit: 1000 });
     return guildMemberList.map(({ displayName, roles }) => ({
@@ -49,6 +49,9 @@ export class DiscordMemberStats
 
   async fetchStats(userId: string): Promise<UserStats | null> {
     const guild = await this.client.guilds.fetch(this.guildId);
+    if (!guild.available) {
+      throw new Error('guild unavailable');
+    }
     const member = await guild.members.fetch(userId);
     if (!member) {
       return null;
diff --git a/src/adaptor/discord/role.ts b/src/adaptor/discord/role.ts
index f3008c9d..65d30a02 100644
--- a/src/adaptor/discord/role.ts
+++ b/src/adaptor/discord/role.ts
@@ -15,6 +15,9 @@ export class DiscordRoleManager implements RoleManager, RoleStatsRepository {
 
   async addRole(targetMember: Snowflake, newRoleId: Snowflake): Promise<void> {
     const guild = await this.client.guilds.fetch(this.guildId);
+    if (!guild.available) {
+      throw new Error('guild unavailable');
+    }
     const member = await guild.members.fetch(targetMember);
     await member.roles.add(newRoleId);
   }
@@ -24,12 +27,18 @@ export class DiscordRoleManager implements RoleManager, RoleStatsRepository {
     removingRoleId: Snowflake
   ): Promise<void> {
     const guild = await this.client.guilds.fetch(this.guildId);
+    if (!guild.available) {
+      throw new Error('guild unavailable');
+    }
     const member = await guild.members.fetch(targetMember);
     await member.roles.remove(removingRoleId);
   }
 
   async fetchStats(roleId: string): Promise<RoleStats | null> {
     const guild = await this.client.guilds.fetch(this.guildId);
+    if (!guild.available) {
+      throw new Error('guild unavailable');
+    }
     const role = await guild.roles.fetch(roleId);
     if (!role) {
       return null;
diff --git a/src/adaptor/discord/voice.ts b/src/adaptor/discord/voice.ts
index 1114b133..90f30a6a 100644
--- a/src/adaptor/discord/voice.ts
+++ b/src/adaptor/discord/voice.ts
@@ -38,9 +38,10 @@ export class DiscordVoiceConnectionFactory<K extends string | number | symbol>
     guildId: Snowflake,
     roomId: Snowflake
   ): Promise<VoiceConnection<K>> {
-    const guild =
-      this.client.guilds.cache.get(guildId) ||
-      (await this.client.guilds.fetch(guildId));
+    const guild = await this.client.guilds.fetch(guildId);
+    if (!guild.available) {
+      throw new Error('guild unavailable');
+    }
     const channel =
       guild.channels.cache.get(roomId) || (await guild.channels.fetch(roomId));
     if (!channel) {