Error on multi-value column updates

[jmeats]

The scenario is: 

A SharePoint list with a required choice column which is set to allow multiple values to be selected each item

A workflow which at one point needs to update a different column in the SharePoint list item. 

In the past, I have built workflows that have an Update Item action. For the required column, I would set the field input in the array option (as opposed to the value option) and dynamically populate with the exact same value from the Get Item action earlier in the workflow because I want the contents of this field not to change. This has previously worked, and I have workflows which were built using this method that are still active and working exactly as they should. 

However, when I try to create a new workflow using this method, I get the following error. 

The 'inputs.parameters' of workflow operation '<Task Name>' of type 'OpenApiConnection' is not valid. Error details: The API operation does not allow writing a value for parameter 'item/<Column Name>/Id'. This parameter is read only.

This error is occurring for every column that allows multiple values - People, Choice, and Managed Metadata. 

The workaround seems to be to initialize an array variable, use an apply to each loop for the column value, append each value to the array variable, and then set the field in the Update Item action to the array variable. This is a lot of extra work when you have several columns getting this error! And it's infuriating when the simpler method worked on workflows I built a couple of years ago. 

Aside from being annoying, this workaround isn't an option if you have a workflow updating multiple list items in a loop and you want to have concurrency. The workflow I am trying to build is getting multiple list items, entering an apply to each loop, getting the individual item, doing various actions based on the data in that list item, and then updating that specific list item with the result. I want these loops to run with concurrency, but if I have to have an array variable I'm using as a temporary placeholder to store the values in a multiple-value column, this isn't going to work, because multiple parallel instances will be trying to write to that variable at the same time and the lists items will update with the wrong information in this column. 

Looking at other people raising this error, it looks like it's starting occurring for multiple people from about August last year. Did Microsoft release an update that broke this fairly basic functionality? 

[jmeats]

I've replicated the issue on another tenant with a much simpler workflow. 

This is the way the Update Item task is configured. 

There are workflows running that use this method that are still working - why is this now broken? 

[jmeats]

Does anyone have a solution for this? 

Or an answer for why Microsoft broke a thing that was working? 

[jmeats · Accepted solution]

Answering my own question. I was able to make this work using the Select action. 

I had to have the extra Get item inside the loop because if I tried to use the Get Items step, Flow kept getting confused and creating loops inside the loop. 

For each of the multi-value choice or managed metadata fields, I used Select and mapped the Value. For the people fields, I used Select and mapped Claims. 

Then in the Update item step, I could use the Output from these steps. 

Because I'm not using a variable that's shared across the loops, I could enable concurrency and it seems to work without getting the values muddled. 

[roxy1]

I thought I was going crazy as I also have older existing flows that are working with no problem, and are now getting the error message the same as you with newly created flows. Glad to have stumbled on your post to help me feel less insane!