I have the same issue occuring sing the migration to 2.1.
I think that this happens in certain cases when querying a reflection that is referenced by another VDS, which has itself reflections.
I needed to deactivate the depending reflections, and reactivate them, from the parent to the children.
The error log mentions columns that have nothing to do with the query executed.
Original: RecordType(BIGINT distri_id, VARCHAR(65536) swntid, VARCHAR(65536) rfr, BIGINT nbrefret, DOUBLE prc, BIGINT is_preview, BIGINT auto, BIGINT is_bot_traffic, BIGINT v, VARCHAR(65536) pid, VARCHAR(65536) module, VARCHAR(65536) rfr2, VARCHAR(65536) iid, BIGINT is_tablet, VARCHAR(65536) c_cfduid, VARCHAR(65536) utm_source, VARBINARY(65536) opscode, DOUBLE avgdist, DOUBLE avgpc, ANY lang, ANY area, BIGINT nbres, VARCHAR(65536) pageid, VARBINARY(65536) currency, VARBINARY(65536) geoip_city, VARCHAR(65536) os, VARBINARY(65536) geoip_country, VARCHAR(65536) sids, BIGINT is_bot, TIMESTAMP(3) ts, VARCHAR(65536) wtbid, VARCHAR(65536) reqpid, BIGINT is_mobile, VARCHAR(65536) sid, VARCHAR(65536) action, VARCHAR(65536) type, VARCHAR(65536) fmt, VARCHAR(65536) browser, VARCHAR(65536) dir0, VARCHAR(65536) dir1, VARCHAR(65536) dir2, VARCHAR(65536) dir3, VARCHAR(65536) geoip.country, BIGINT is_pc, VARCHAR(65536) ct, VARCHAR(65536) utm_campaign, VARCHAR(65536) os_version, VARCHAR(65536) utm_content, ANY avpid, VARCHAR(65536) browser_version, VARCHAR(65536) rfr2_domain, VARCHAR(65536) c_swntid, VARCHAR(65536) utm_term, VARCHAR(65536) utm_medium, ANY dlv, VARCHAR(65536) rfr_domain, BIGINT $dremio$update$)
Replacement: RecordType(BIGINT distri_id, VARCHAR(65536) swntid, VARCHAR(65536) rfr, BIGINT nbrefret, DOUBLE prc, BIGINT is_preview, BIGINT auto, BIGINT is_bot_traffic, BIGINT v, VARCHAR(65536) pid, VARCHAR(65536) module, VARCHAR(65536) rfr2, VARCHAR(65536) iid, BIGINT is_tablet, VARCHAR(65536) c_cfduid, VARCHAR(65536) utm_source, ANY opscode, DOUBLE avgdist, DOUBLE avgpc, ANY lang, ANY area, BIGINT nbres, VARCHAR(65536) pageid, VARBINARY(65536) currency, ANY geoip_city, VARCHAR(65536) os, ANY geoip_country, VARCHAR(65536) sids, BIGINT is_bot, TIMESTAMP(3) ts, VARCHAR(65536) wtbid, VARCHAR(65536) reqpid, BIGINT is_mobile, VARCHAR(65536) sid, VARCHAR(65536) action, VARCHAR(65536) type, VARCHAR(65536) fmt, VARCHAR(65536) browser, VARCHAR(65536) dir0, VARCHAR(65536) dir1, VARCHAR(65536) dir2, VARCHAR(65536) dir3, VARCHAR(65536) geoip.country, BIGINT is_pc, VARCHAR(65536) ct, VARCHAR(65536) utm_campaign, VARCHAR(65536) os_version, VARCHAR(65536) utm_content, ANY avpid, VARCHAR(65536) browser_version, VARCHAR(65536) rfr2_domain, VARCHAR(65536) utm_term, VARCHAR(65536) utm_medium, ANY dlv, VARCHAR(65536) rfr_domain, BIGINT $dremio$update$).
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:383) ~[guava-20.0.jar:na]
at com.dremio.reflection.bup.ReplacementShuttle.replace(ReplacementShuttle.java:37) ~[dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.ReplacementShuttle.replace(ReplacementShuttle.java:33) ~[dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.SubIterator.replicateWithReplace(SubIterator.java:100) ~[dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock.generateAlternativeBlocks(MatBlock.java:544) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock.access$100(MatBlock.java:47) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock$2.apply(MatBlock.java:199) ~[dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock$2.apply(MatBlock.java:195) ~[dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.google.common.collect.Iterators$7.transform(Iterators.java:750) ~[guava-20.0.jar:na]
at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47) ~[guava-20.0.jar:na]
at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:252) ~[guava-20.0.jar:na]
at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:209) ~[guava-20.0.jar:na]
at com.google.common.collect.FluentIterable.toList(FluentIterable.java:614) ~[guava-20.0.jar:na]
at com.dremio.reflection.bup.MatBlock.matchLeafNode(MatBlock.java:200) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock.determineLeafIterators(MatBlock.java:183) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock.generateAlternativeBlocks(MatBlock.java:490) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock.generateCandidates(MatBlock.java:441) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
… 16 common frames omitted
2018-09-07 07:47:30,824 [246dd2ec-9fa0-0f0c-a8a3-2ac959ad8f00:foreman] INFO com.dremio.reflection.bup.MatBlock - User Error Occurred [ErrorId: 6b3067a4-5a27-4d57-ab7d-3cc85a151001]
com.dremio.common.exceptions.UserException: Failure while attempting candidate reflection substitution for 8ca4112a-16bd-4734-9c25-851b36bcfc76
at com.dremio.common.exceptions.UserException$Builder.build(UserException.java:746) ~[dremio-common-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.MatBlock.generateCandidates(MatBlock.java:474) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.reflection.bup.BupFinder.generateAlternatives(BupFinder.java:125) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.acceleration.substitution.DremioSubstitutionProvider.generateNewAlternatives(DremioSubstitutionProvider.java:179) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.acceleration.substitution.DremioSubstitutionProvider.findSubstitutions(DremioSubstitutionProvider.java:141) [dremio-extra-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.acceleration.substitution.AccelerationAwareSubstitutionProvider.findSubstitutions(AccelerationAwareSubstitutionProvider.java:67) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.DremioVolcanoPlanner.registerMaterializations(DremioVolcanoPlanner.java:70) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at org.apache.calcite.plan.volcano.VolcanoPlanner.findBestExp(VolcanoPlanner.java:605) [calcite-core-1.16.0-201807312206090258-e1b02e7.jar:1.16.0-201807312206090258-e1b02e7]
at org.apache.calcite.tools.Programs$RuleSetProgram.run(Programs.java:368) [calcite-core-1.16.0-201807312206090258-e1b02e7.jar:1.16.0-201807312206090258-e1b02e7]
at com.dremio.exec.planner.sql.handlers.PrelTransformer.transform(PrelTransformer.java:444) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.sql.handlers.PrelTransformer.convertToDrel(PrelTransformer.java:222) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.sql.handlers.PrelTransformer.convertToDrel(PrelTransformer.java:280) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.sql.handlers.query.NormalHandler.getPlan(NormalHandler.java:47) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.planner.sql.handlers.commands.HandlerToExec.plan(HandlerToExec.java:69) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at com.dremio.exec.work.foreman.AttemptManager.run(AttemptManager.java:291) [dremio-sabot-kernel-2.1.4-201808302048550610-0981242.jar:2.1.4-201808302048550610-0981242]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_181]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_181]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_181]
Caused by: java.lang.IllegalArgumentException: Row types didn’t match.