The following error can appear in MS Project. In my case it was when I was attempting to insert sub projects into a Master Schedule. It may also appear in regards to modifying resource custom fields such as the RBS.
It seems that MS Project is unable to handle custom lookup fields that have a selected value longer than 128 characters. Particularly when using ‘multi-value custom fields’ there is little to no restriction on the length of values that are selected.
The look up table itself will not allow you to create values that are too long, but when selecting multiple values the end result can be longer than 128 characters. These values can be selected in Project Web Access (PWA) when editing project properties but when trying to insert the project as a sub project of another, we receive the above error.
To identify which field is causing the issue:
– Right click and insert all of the project level custom fields that could be the culprit.
The problem field will be the one without a value at the project summary task level. This is the cause of the error message.
There a few possible workarounds that could resolve this error:
– Modify the custom field lookup table to utilise the description field for lengthy values
– Modify the custom field lookup table to be considerably abbreviated/shortened in text
– Create multiple custom fields that only allow single values to be selected
– Request users to manually type values into a free text field
As you can see the workarounds are not desirable, however depending on your reporting requirements they may well resolve the immediate issue.