Conflict error but there is no conflict

[RonHappel]

Hi all,

Sometimes I'm getting conflicts errors on a SharePoint list when I know for sure nobody else is using the record.

Does anybody know why this happens?

The statement that causes sometimes the error is:

Patch(Tabel3Mnd;First(Filter(Tabel3Mnd;Achternaam=AfAchternaam And Voornaam=AfVoornaam And JaarMaand = AfJaarMaand));{LaatsteSaldo:AfSaldo-1;
DatumsAf:Left(Concat(HulpTabelAfb;Result&"#");Len(Concat(HulpTabelAfb;Result&"#"))-1);
Groepen:Left(Concat(HulpTabelGrp;Result&"#");Len(Concat(HulpTabelGrp;Result&"#"))-1)}))

It worked fine for more than 1,5 years.

Thanks, Ron

[poweractivate]

@RonHappel 

Where is the Patch statement being used? 

Check if adding a Refresh after the end of this Patch helps.

Also check if in addition to the above:

1. Disabling the whole form immediately right before the Patch and preventing any other Patch to this record (using variable).

2. Having a Custom Timer that after 1 second or 2 seconds, sets the variable back and re-enables the form.

The reason for the above, is that it is possible that even if you will have the Refresh, the subsequent Patch will be operating on the stale record, so it will prevent the change. It shows this error message about another user - actually that user could be you yourself operating on a stale version of the record.

For a superior solution to any of the above, if the above is not enough, you may need to consider something like this:

1. Hidden custom column such as "customVersion" and hidden field which will reference this custom column's current value for the current record being worked on. If the form has not been edited yet by this client, a second hidden field will contain the same value for the moment (see below).

2.  When value is Patched, whole form is disabled immediately, then new  unique "customVersion" value (e.g. based on random value + current Timestamp for instance) is generated by the Power App and then this value kept in another hidden field - the value of this other hidden field is modified to now contain this new value, and also sent to SharePoint along with the Patch.

2b. Rather than to use Timers or anything very complicated, maybe instead the whole form could be disabled immediately because of a condition like this: If(Label1.Text = Label2.Text,FormMode.Edit,FormMode.View) - then once the value of Label was set to different value immediately before Patch, the form has already been instantly set to the View mode just before the Patch has even been issued. At the end of this formula, the Refresh(YourDataSource) is also there.

3. Once the Datasource Refresh has completed, the first hidden field should update with the correct "customVersion" value . This should end up causing the form to become in Edit mode again. After this, it should be not as easy to face this problem again. Now it should only show that error, if someone else really was using it at the same time.

Check if the above might help you for guidance.

Also check if the below similar topic helps:

Save conflict error when patching -Powerapps 

[RonHappel]

Thanks for your reply and help. I will try to explain this further.

The app shows a selection of the database (SharePoint lists) in a Gallery.

The purpose of the app is to update a balance ((Saldo) for a selection of items (Persons) in the Gallery. Any update is logged in a Transaction (SharePoint List too).

The user sees a particular person and selects the ‘Kies’ button for that item (Person). He continues and selects another person, and so on.

Immediately after an individual selection all buttons in the Gallery are disabled, followed by the Patch of the Transaction and the Patch of the Person. The relevant fields updated in the Person-record are Saldo and LaatsteAfboeking (timestamp of the transaction).

The Gallery contains a hidden column with the value of the field LaatsteAfboeking. Only when this field changes in the Gallery the buttons will be activated and therefore selectable. My assumption here is that the Gallery has been refreshed because it now shows the hidden value in the column LaatsteAfboeking. In addition the new balance (Saldo) is shown.

With regard to the example above let’s assume the user selects ‘Beukers’ -> buttons are disabled -> patches are initiated -> Gallery refreshes - > LaatsteAfboeking changes -> buttons are active again.

Now the user selects ‘Chotoe’. A conflict error occurs on the Patch issuing the update in the Transaction list. This transaction record is physically a different record (SharePoint List item).

My assumption is that when the app issues the Patch on ‘Beukers’ the actual update is delegated to the back-end process and the app itself has no control anymore. Subsequently the Patch on ‘Chotoe’ is initiated and it signals a conflict because the patch on Beukers is not completed yet by the back-end process. My assumption is based on the fact that the conflict error occurs occasionally. Probably when the Microsoft servers are slower than usual. Strange however is that the Gallery refreshes after the Patch on Beukers which activates the buttons.

I haven’t used a Refresh statement after the Patch because this will take a lot of time due to the size of the SharePoint list making the whole update process unacceptable for the user.

I’ve tried a timer in addition the hidden field in the Gallery, but selecting the right duration is difficult.

It looks like I’ve implemented your hidden field solution, however I’m not completely sure it’s the same kind of solution.

I hope the above clarifies the problem further and it will help to find a solution.

By the way what do you mean by ‘stale record’?

Kind regards, Ron