Connection Failed - Action failed due to server error

This page gives you the steps to take when you receive the Connection Failed - Action failed due to server error when trying to connect SlapFive/Workato to Salesforce.

The most likely cause

When Workato tries to connect to Salesforce but only shows “Connection Failed – Action failed due to server error,” 90% of the time it means Salesforce is blocking Workato from signing in. Here’s what you need to do.

Go to Setup → Connected Apps → Connected Apps OAuth Usage.

You’ll see a list of Connected App that users have recently authenticated with. Look for one of the following:

  • Workato

  • Workato connector

  • Workato OAuth Connector

Salesforce does not literally put a red “Blocked” label here. Instead, a Connected App becomes effectively blocked when the app is restricted to “Admin approved users only”. This blocks the Integration User unless they're explicitly granted access.

How to unblock:

  1. In the Workato connector row, click the Manage App Policies link.

  2. Scroll to the OAuth Policies section and look at the Permitted Users field. If it says:

“Admin approved users are pre-authorized”

…then Salesforce is blocking Workato for all users who haven’t been assigned. To unblock it for your Integration User, there are two options:

Option 1 — Assign via Permission Set

  1. Go to Setup → Permission Sets

  2. Open the Permission Set used for API integrations

  3. Click Assigned Connected Apps

  4. Add Workato connector

  5. Assign the Permission Set to the Integration User

Option 2 — Assign via Profile

  1. Go to Setup → Profiles

  2. Open the Integration User’s profile

  3. Scroll to Connected App Access

  4. Check the box next to Workato connector

  5. Click Save

Once assigned, Workato is unblocked for that user.

If this doesn't eliminate the error, continue below.

Other possible causes

The other 10% of the time that error appears, it is something more obscure. Here are the things to check, in order of likelihood.

1. Confirm the Workato Connected App is installed

Go to Setup → Connected Apps → Manage Connected Apps

Check that one of these appears in the list:

  • Workato connector

  • Workato

  • Workato OAuth Connector

If the Workato app does not appear, the connection will fail.

Fix: You’ll need to install the Workato managed package so the Connected App becomes visible and assignable.

2. Verify that the Integration User has the right permissions

Salesforce only issues API tokens when the user has the necessary permissions.

Confirm the Integration User has:

  • API Enabled

  • Access to the objects and fields shown here.

Missing object access or Record Type assignments commonly trigger this error.

3. Check if your org is blocking non-installed Connected Apps

Some Salesforce orgs enforce a security policy that blocks Connected Apps that are not explicitly installed in the org.

If this setting is active:

  • Workato’s standard Connected App will be blocked

  • You will see connection failures with no detailed error message

Fix: Install the Workato Installed Package, which adds an org-local version of the Workato Connected App that Salesforce will trust.

4. Make sure Workato is connecting to the correct domain

If your Salesforce org recently enabled My Domain or adopted Enhanced Domains, older connection settings no longer work.

Fix: Reconnect the Workato connection using your My Domain URL, for example: https://yourdomain.my.salesforce.com

5. Check for IP restrictions or token policies

If your org uses strict login or token policies, Salesforce may block Workato’s login attempt.

Please check:

  • Setup → Login Access Policies

  • Setup → Network Access (Trusted IP ranges)

  • Connected App Session Policies for the Workato app

If Workato’s IP ranges are not trusted or token policies are too strict, OAuth login will fail.

6. Refresh the connection in Workato

Sometimes the simplest fix works:

  1. Go to the Workato connection

  2. Click Reconnect

  3. Re-enter the credentials for the Integration User

  4. Make sure your browser does not block the Salesforce login popup

This forces Salesforce to issue a fresh OAuth token.

7. If the issue persists: capture the Salesforce Login History

In Salesforce:

Setup → Users → Integration User → Login History

Look at the most recent failed login entry. The error code there (for example, invalid_grant, IP restricted, user hasn’t approved this app) will tell us exactly what Salesforce is rejecting.

Send us that line and we can pinpoint the fix instantly.

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