Threads Account Migration From Mastodon: Follower Carry-Over Limits

When you move your social media presence from Mastodon to Threads, you may expect your followers to automatically transfer. This is not how the current system works. The ActivityPub protocol that powers both platforms does support account migration, but Threads enforces specific limits on how many followers can carry over. This article explains the exact follower carry-over limits, the technical reasons behind them, and the steps you must take to migrate your account successfully.

Why Follower Carry-Over Is Limited in Threads

Threads and Mastodon both use the ActivityPub protocol, but they implement account migration differently. On Mastodon, a full account migration moves all followers, follows, and posts to a new account. The old account becomes a redirect that points followers to the new location. Threads does not support this full migration model. Instead, Threads treats account migration as a profile transfer that moves a limited set of data.

Technical Root Cause

Threads stores follower relationships in its own database, not in a shared ActivityPub inbox. When you initiate a migration from Mastodon to Threads, the Threads server sends a Move activity to each Mastodon follower. Each follower must manually approve the move by clicking a link in their Mastodon notifications. If a follower does not approve, they remain subscribed to your old Mastodon account. The 500-follower limit is a Threads server-side cap designed to prevent spam and server overload during the manual approval process.

What Data Migrates vs What Stays Behind

Only your Mastodon followers can carry over. Your Mastodon posts, bookmarks, lists, and direct messages do not transfer to Threads. Threads creates a new profile with your chosen username and displays a link to your old Mastodon profile. The old Mastodon profile remains active but posts a notice that you moved to Threads.

Steps to Migrate Your Mastodon Followers to Threads

Before you start, make sure your Threads account is public. Private accounts cannot receive followers from Mastodon. You also need access to your Mastodon account to create a verification alias.

1. Set up a verification alias on Mastodon
   On Mastodon, go to Profile > Edit profile > Profile metadata. Add a new row with the label “Threads” and the value being the full URL of your Threads profile. Save the changes. This alias proves you own both accounts.
2. Start the migration on Threads
   Open the Threads app or website. Go to Settings > Account > Transfer a profile. Tap or click “Transfer from another service.” Threads will ask for the URL of your Mastodon profile. Paste the full URL, for example https://mastodon.social/@yourusername.
3. Verify the alias on Threads
   Threads checks the profile metadata on your Mastodon account. If it finds the alias you created, Threads confirms the ownership. If the alias is missing or incorrect, Threads shows an error and you must fix the metadata before proceeding.
4. Authorize the Move activity on Mastodon
   After Threads verifies the alias, your Mastodon account receives a notification. Log in to Mastodon and open your notifications. You will see a message that @threads.net wants to move your followers to a new account. Click “Approve.” Mastodon then sends a Move activity to each of your followers.
5. Wait for followers to approve manually
   Each Mastodon follower receives a notification asking them to approve the move. They must click “Follow” on your new Threads profile. Threads counts only the followers who approve within the migration window, which is 7 days. After 7 days, the migration ends and any unapproved followers are left behind.

If the Migration Fails or Followers Do Not Carry Over

Migration Error: “Alias not found”

Threads cannot find the verification alias on your Mastodon profile. Check that the profile metadata label is exactly “Threads” and the value is your Threads profile URL. The URL must start with https://www.threads.net/@. If you use a different label or misspell the URL, Threads rejects the migration. Delete the metadata row and recreate it with the correct format.

Follower count shows 0 after migration

This happens when none of your Mastodon followers approve the move. Mastodon does not auto-approve migrations. Each follower must manually click the follow button on your new Threads profile. To increase approval rates, post a message on Mastodon before starting the migration. Tell your followers to expect a move notification and ask them to approve it. You can also share your Threads profile link directly so they can follow you manually without waiting for the notification.

Only part of your followers carried over

Threads limits the migration to 500 followers. If you have more than 500 Mastodon followers, only the first 500 who approve the move will carry over. The remaining followers are not transferred. To bring more followers, you must wait 30 days and then perform a second migration. During the second migration, Threads checks for any new followers who approved since the first migration. Followers who already transferred are not counted again.

Threads vs Mastodon Account Migration Features Compared

Item	Threads	Mastodon
Follower carry-over limit	500 followers per migration	Unlimited (all followers transfer)
Post migration	Not supported	All public posts transfer
Manual approval required	Each follower must approve individually	Follower approval is optional (auto-follow by default)
Cooldown period	30 days between migrations	30 days between migrations
Old account behavior	Old Mastodon account remains active but shows a redirect notice	Old account becomes a redirect that cannot post

Threads migration is more restrictive than Mastodon’s native migration. If you have a large Mastodon following, plan to migrate in batches over several months. Each batch moves up to 500 followers and requires a 30-day wait before the next attempt.

Conclusion

You can now migrate your Mastodon followers to Threads using the profile transfer feature. The 500-follower limit means you may need multiple migrations over time if your audience is large. After each migration, check your Threads follower count and schedule the next transfer after the 30-day cooldown ends. For a smoother migration, post a pre-announcement on Mastodon asking followers to watch for the move notification. This increases the approval rate and reduces the number of followers lost in each batch.