Error "We encountered a problem" When Connecting Outlook or Gmail Integration with an Inbox

This generic error has several causes, and the following can assist.

1. Verify that Inbox is causing the error

1. Go to the affected user's User Details page.
2. Delete the Inbox related Permission Set Assignments.
3. Delete the Inbox Permission Set License Assignments.
4. Restart Outlook integration.

If the side panel loads accordingly, continue with the following troubleshooting.

2. Internet Explorer settings to allow session and 3rd-party cookies:

1. Bring up the RUN command box by using the Windows and R key combination and enter Inetcpl.cpl and press Enter.
2. Select the Privacy tab.
3. Click Advanced.
4. Select the override automatic cookie handling checkbox.
5. Select Accept for first and third party cookies.
6. Select Always allow session cookies.

3. Relax IP Restrictions

1. Navigate to the Connected Apps from Setup

2. Click Edit beside the SalesforceIQ app. 
3. Select Relax IP Restrictions in 'IP Relaxation' field.

4. Check the Inbox Connected App is not blocked

1. Go to Setup
2. Search for "Connected Apps OAuth Usage" in the search option on the left side.
3. Select Connected Apps OAuth Usage.
4. In the list of Apps, look for Salesforce IQ.
5. Select Unblock.
6. Once you have unblocked Salesforce IQ, remove the Inbox permission set and Inbox license that is assigned to the affected user.
7. Re-assign the Inbox permission set and Inbox license to the user.
8. Ask the user to reconnect the email account under Settings | Email | Connected Accounts.
9. Reload the side panel in the Outlook App.

5. Verify the setting "Admin approved users are pre-authorized"

If "Admin approved users are pre-authorized" is selected, this adds a Profile section at the bottom of the page and listing "Profiles" can block access to Inbox.  The recommended setting is "All users may self-authorize."

6. Check Salesforce Allowlist for IP Addresses
 

For seamless usage of our Salesforce Inbox product, visit the Salesforce Email Integration Security Guide for a specific list of IP addresses to allow.  Also ensure that app.salesforceiq.com, api.salesforceiq.com, app-frankfurt.salesforceiq.com, api-frankfurt.salesforceiq.com have access to any EWS endpoint.

Please refer to the Salesforce Email Integration Security Guide document for more information on allowlisting and any other information regarding Salesforce Inbox.

7. Enable API permissions for the affected profiles

If the issue is only happening to specific profiles, check if 'API Enabled' is activated in the System Permissions of the said profile.

1. Navigate to Profiles from Setup.

In Salesforce Classic: Setup | Manage Users | Profiles
In Lightning Experience: Setup | Users | Profiles
 

2. Access the profile of the affected User.
3. Select System Permissions under System.
4. Click on Edit.
5. Select API Enabled if it is disabled.
6. Click Save.

8. Connected Accounts

One last item to check is after making sure the users are assigned to the Inbox with or without Einstein Activity Capture permission set, check to make sure that their email account is connected from their personal Settings | Email Settings in Salesforce Lighting as instructed here:

1. Click on your Profile icon and select Settings | Email | Connected Accounts | Email and Calendar Accounts.
2. Check under Connected Accounts. Your email address should be connected; you will see a disconnect button if it is. If the button shows Reconnect, go ahead and click on Reconnect to connect your email.
3. If there is no connected account, you can either manually connect one by clicking on the New Account button or try to login via the Outlook integration Side Panel and finish logging in.

 Please refer to Connect Your Email and Calendar to Salesforce with Einstein Activity Capture for more information.