This is rather weird query - why you need a service if you already have the label bound?

Here is the real query – the relevant part is: either a statement is a normal statement and has a proper object (?object), in which case I want its label, or it’s a “no value” statement, in which case I want to bind ?objectLabel to "no value"@en. (In the real query, in the end I had to use rdfs:label anyways to make the GROUP_CONCAT in the SELECT clause work.)

Direct link to the full query.

@WikidataFacts the query you provided however works. Could you provide a full query that didn't work for you? That'd make figuring out the problem easier.

Here’s a variation that triggers the error: query

It returns some partial results before the error message because the error is only triggered when the first “no value” is reached, in “abbot” – “applies to territorial jurisdiction” – no value. (To see the result list, comment out or remove line 24.)

Looks like Blazegraph issue, filed https://jira.blazegraph.com/browse/BLZG-8547.

I think these are the same issue:

SELECT ?x ?xLabel WHERE {
  BIND(wd:Q42 AS ?x).
  BIND("Douglas Adams"@en AS ?xLabel).
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}

Link

SELECT ?x ?xLabel WHERE {
  VALUES (?x ?xLabel) {
    (wd:Q42 "Douglas Adams"@en)
  }
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}

Link

(Motivation for the second example: I have a selection of values with predefined labels, which may not match the Wikidata labels, but I still want to use the label service for other, unrelated variables.)

Change 533112 had a related patch set uploaded (by Igor Kim; owner: Igor Kim):
[wikidata/query/blazegraph@master] Support for uncertainVars in ServiceNode

https://gerrit.wikimedia.org/r/533112

Change 533117 had a related patch set uploaded (by Igor Kim; owner: Igor Kim):
[wikidata/query/rdf@master] Fix NME on bind variable both by LabelService and some other clause

https://gerrit.wikimedia.org/r/533117

Change 533112 merged by Smalyshev:
[wikidata/query/blazegraph@master] Support for uncertainVars in ServiceNode

https://gerrit.wikimedia.org/r/533112

Change 533117 merged by jenkins-bot:
[wikidata/query/rdf@master] Fix NME on bind variable both by LabelService and some other clause

https://gerrit.wikimedia.org/r/533117