Is it possible to set a property bag value via CSOM without having tenant permissions?

Question

I'm trying to use my backend CSOM app with context of Site Collection Administrator service account to programmatically set a property bag value to store some settings for my frontend extension app.

I've tried doing it in 2 ways:

web.SetPropertyBagValue("name", "value");
ctx.ExecuteQuery();

and

web.AllProperties["name"] = "value";
web.Update();
ctx.ExecuteQuery();

but in both cases I get the error:

{"Access denied. You do not have permission to perform this action or access this resource."}

Is there really no way a Site Collection Administrator could set a property bag in SharePoint Online? I'm asking this because I've had similar issue when trying to delete a site, in which case according to a few sources on the Internet this operation could also be done only by tenant administrator but I found a method:

ctx.DeleteSiteAsync()

which turned out to be successfully deleting a site without tenant permissions. So I hope maybe there is also a solution here.

Answer 1

@Mariusz Ignatowicz

Just Test you code in my SPO modern site, It works fine here:

Then I enabled DenyAddAndCustomizePages as @m1g suggested, it will prompt "Access denied. You do not have permissio...."

Connect-SPOService -Url https://[tenant]-admin.sharepoint.com -credential [email protected]

Get-SPOSite -Identity https://[tenant].sharepoint.com/sites/comm|select DenyAddAndCustomizePages
### o is disable, 1 is enable
Set-SPOSite -Identity https://[tenant].sharepoint.com/sites/comm -DenyAddAndCustomizePages 1  

So i think you need to turn off DenyAddAndCustomizePages first, then it should be fixed.

BR