• This error mostly occurs when trying to open a task that you (or another task participant) already completed. For example, clicking on a task notification email when you had previously completed the task via worklist, or clicking on a task notification sent to a group of users and another user has already completed that task.  
• The error can also happen if another user had opened the task, but not completed the task yet. This is especially likely in a multi-participant scenario where another user may have opened the task but is still working on the task or forgot to complete the task. 
• The error can occur when the serial number specified to open the task is invalid, for example if a user tried to guess or hack the serial number value for a task link. 
• The error can occur when the incorrect state is being used in the Workflow or Form.
• The error can occur when there is a duplicate "If workflow task is [User task name]" in the form rules for the form being opened.
• The error can occur when the task is allocated to a different user in the decision step in the Workflow

• Verify that the task is available for the current user. The easiest way to do this is to open the user's worklist in K2 Workspace and verify if the specified task is still in the current user's worklist. 
• Check the Worklist Item's status to see if the task is opened by another user. If the status is set to "Allocated", the error can occur. Use the other user's Workspace or the K2 Management Site to Release the worklist item and make the task available to all users again. 
• Ensure the correct Form State value is used in the task link URL. 
• The issue can be caused by two conditions that contain "If workflow task is [User task name]" statement. Remove the duplicate condition check in the form rule.

• This error usually happens when K2 cannot match the specified task serial number to the person who is attempting to open the task. 
• The current user may be attempting to open a task using a task link/URL that contains a serial number allocated to another user. 
• This error can occur when there is a trailing space in the UserID property for the user who is trying to open the task
• This error can occur when the incorrect or a missing domain is used to connect to K2
• This error can occur when the account used for SmartActions is also being used in another environment
• This error can occur when the ExpireOn or MembersExpireOn column in the Identity Cache system  has not updated

• Ensure that the task link is actually valid for the current user. One way to validate this is to see if you can see the same task link on the current user's K2 worklist in the k2 workspace. 
• Ensure the correct domain and user credentials are used to open the task.
• A dedicated mailbox account is required for SmartActions. See the SmartActions topic for more information.
• To troubleshoot issues with the Identity service, see the Identity.Identity table topic. 

• This error mostly occurs when trying to open a task that you (or another task participant) already completed. For example, clicking on a task notification email when you had previously completed the task via worklist, or clicking on a task notification sent to a group of users and another user has already completed that task.  
• This error can occur when the account used for SmartActions is also used in another environment.

• Verify that the task is available for the current user. The easiest way to do this is to open the user's worklist in K2 Workspace and verify if the specified task is still in the current user's worklist. 
  Check the Worklist Item's status to see if the task is opened by another user. If the status is set to "Allocated", the error can occur. Use the other user's Workspace or the K2 Management Site to Release the worklist item and make the task available to all users again. 
• To resolve this error a dedicated mailbox account is required for SmartActions. See the SmartActions topic for more information.

• This error can occur if the user attempts to take an action on the task that is not defined as a valid action in the workflow design, For example, the user may have attempted to select/enter an "Approved" action when the action name is actually "Approve".
• This error can occur when incorrect user actions are placed in Workflow and Form load rules. For example, the workflow definition of the available actions is "Approve" and "Reject" but the form load rules are using action names "Approved" and "Rejected". 

• Ensure that the specified action value exactly matches the action name as defined in the workflow design. 
• Recreate the actions in the Form load rules.

This error most often occurs when the K2 service is not running on the server hosting the K2 server service.

Start the K2 service on the machine(s) hosting the K2 server service.

Invalid value is being passed in the underlying code. 

Run a Fiddler trace and in the XML tab see if the following error is displayed: Name cannot begin with the '<' character, hexadecimal value 0x3C. If you see this error in the Fiddler trace, delete all instances of the workflow encountering this error. Start new instances of the process and the error no longer persists

• This error can occur when the SMTP connection closes intermittently
• This error can occur when the Search String for E-Mail addresses are incorrect
• This error can occur when there is no connection string for the destination E-Mail Address

• Ensure you have upgraded your K2 environment to the latest version of K2
• Update your E-Mail Address to a Static E-mail Address
• To adjust the SMTP connection value:
  1. Navigate to the ConnectionStringEditor tool
  2. Right-click the tool and select 'Run as Administrator'
  3. On your connection string, change Authentication from 'Anonymous' to 'Plain'
  4. Enter values for the User ID and Password fields
  5. Click the Save icon in the top left corner of the window
  6. Restart the K2 Service to ensure the changes have been made

• This error occurs when attempting to complete a task using SmartActions. 
• This error can occur when you have a custom task email notification that does not include the serial number for the task. The K2 server needs to know the serial number to associate the Smart Action with the proper task
• This error can occur when the account used in the SmartActions mailbox is used across multiple K2 environments
• This error can occur when multiple word synonyms are used in responses when replying to SmartAction emails 

• Add the task serial number to your custom task notification
• Ensure that a unique account is used for the SmartActions mailbox. It is a requirement for each K2 environment to have a unique account when using SmartActions, to prevent multiple servers from processing the same messages
• Multiple word synonyms used to respond to SmartAction emails are not currently supported. See the K2 SmartAction Synonyms topic for more information

This error can occur when the WorklistItemRedirect stored procedure was not updated in the K2 database following an upgrade. 

This error is resolved in Fix Pack 39. Ensure your K2 environment is updated to the latest version of K2.

This error can occur when an upgrade fails and the Reports.kspx and Reports_update1.kspx packages fail to deploy during the upgrade process

• Run a Repair using the K2 installation media. If you had any Fix Packs installed on your K2 environment prior to running the repair, install the Fix Packs once more after completing the repair.
• To resolve this error manually redeploy the Reports.kspx and Reports_update1.kspx packages from the K2 installation media. 

This is a known behavioral issue. 

• To resolve the following error, follow the steps below:

1. Make a backup of both the Designer and Runtime web.config files
2. Within these files, search for the following node: <caching>
3. Find <add name='RT profile".. within here there should be a varyByCustom entry
4. Update this entry to include 'Browser', for example, change varyByCustom="userversion;userculture;jq-legacy" to varyByCustom="userversion;userculture;jq-legacy;Browser"
5. After making the edits save the changes, then reset IIS.

• This issue can occur when the UseBundledFiles and Forms.PostRenderCombining.Enabled entries are set to the incorrect values in the SmartForms Runtime web.config file.
• This issue can occur when the windowsAuthentication, useKernelMode and useAppPoolCredentials entries are set to false in the Workspace web.config file.
• Known Issue on K2 Cloud update 6 Fix Pack 6 and later. 
• This issue can occur due to the following errors that you may see through F12 Browser Developer Tools and/or the Windows Event Log:
  • Refused to apply style from 'company site/CombinedResource.ashx?d= because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.
  • Failed to get resource:[Path Platinum 2 css]
    Exception:SourceCode.Forms.AppFramework.AsyncException: Asynchronous operation failed ---> System.Net.WebException:
    The remote server returned an error: (500) Internal Server Error.

• Follow the steps below:
  1. Make a backup of the SmartForms Runtime web.config file.
  2. Open the SmartForm Runtime web.config file and edit the following entries as shown below:
  3. From:
     <add key="UseBundledFiles" value="true" />
     <add key="Forms.PostRenderCombining.Enabled" value="true" /> . 
     To:
     <add key="UseBundledFiles" value="false" />
     <add key="Forms.PostRenderCombining.Enabled" value="false" />
  4. Save the changes, do an IIS reset and restart the K2 service.
• Follow the steps below:
  1. Go to the [Program Files]K2 blackpearlWorkspaceSite folder.
  2. Open the web.config file in a Text Editor.
  3. Search for the below section:
     windowsAuthentication
  4. Then update the authentication section to the below:
     <windowsAuthentication enabled="true" useKernelMode="true" useAppPoolCredentials="true">
     The true options were originally set to false on this environment.
  5. With this update do an IIS reset and restart the K2 service. The Workspace page should load without issue.
•  You can resolve this error by running an IIS reset on your K2 server
• To resolve the issue, confirm that the associated K2 Service account has the required listed folder permissions here. The image below is an example of Service Account permissions on the K2Host ServerBin folder:
  

• The error can occur due to the following:
  • The Application Pool K2 Workspace is running under may be incorrect
  • The Application Pool user may not have the required rights to access the SQL Server the K2 Workspace database is running on
  • The workspace user account has the incorrect permissions on the K2 database

• Restart the K2 Host server Service
• Ensure that the Workspace application pool user account has the  securityadmin permission configured on the SQL Server