MESSAGE: Code exception (see stack trace for error itself) HaplotypeCaller

Hi, all:
I meet some error while call variant with HaplotypeCaller, please help~~ Thanks a lot!
my CMD:
java -jar GenomeAnalysisTK-3.6.jar -T HaplotypeCaller -R Homo_sapiens_assembly38/Homo_sapiens_assembly38.fasta -I SMT.reorder.markdup.reAlign.reCal.bam --emitRefConfidence GVCF --variant_index_type LINEAR --variant_index_parameter 128000 -o SMT.gvcf
the ERROR:
INFO 14:41:23,143 ProgressMeter - chr2:23812214 2.48956422E8 4.0 h 58.0 s 8.5% 47.5 h 43.5 h
INFO 14:42:23,145 ProgressMeter - chr2:25450124 2.48956422E8 4.0 h 58.0 s 8.5% 47.4 h 43.3 h
WARN 14:42:41,261 HaplotypeCallerGenotypingEngine - location chr2:26014393: too many alternative alleles found (7) larger than the maximum requested with -maxAltAlleles (6), the following will be dropped: AATATATATATATAT.
WARN 14:43:17,893 HaplotypeCallerGenotypingEngine - location chr2:26931169: too many alternative alleles found (8) larger than the maximum requested with -maxAltAlleles (6), the following will be dropped: ATGTGTGTGTGTGTGTG, ATGTGTGTG.
INFO 14:43:23,146 ProgressMeter - chr2:27026924 2.48956422E8 4.1 h 58.0 s 8.6% 47.3 h 43.3 h
WARN 14:43:53,267 HaplotypeCallerGenotypingEngine - location chr2:27642958: too many alternative alleles found (9) larger than the maximum requested with -maxAltAlleles (6), the following will be dropped: TATACACACACACACAC, TACACACACACA
INFO 14:44:23,153 ProgressMeter - chr2:28524130 2.48956422E8 4.1 h 58.0 s 8.6% 47.2 h 43.2 h
INFO 14:45:23,155 ProgressMeter - chr2:29933290 2.48956422E8 4.1 h 59.0 s 8.7% 47.2 h 43.1 h
WARN 14:45:26,878 HaplotypeCallerGenotypingEngine - location chr2:30004866-30004882: too many alternative alleles found (7) larger than the maximum requested with -maxAltAlleles (6), the following will be dropped: G.
INFO 14:46:23,156 ProgressMeter - chr2:31296567 2.48956422E8 4.1 h 59.0 s 8.7% 47.2 h 43.1 h
INFO 14:47:23,157 ProgressMeter - chr2:32913035 2.48956422E8 4.1 h 59.0 s 8.8% 47.1 h 43.0 h
INFO 14:48:23,159 ProgressMeter - chr2:33975627 2.48956422E8 4.1 h 59.0 s 8.8% 47.1 h 43.0 h
INFO 14:49:23,161 ProgressMeter - chr2:35160772 2.48956422E8 4.2 h 60.0 s 8.8% 47.1 h 42.9 h
INFO 14:50:23,162 ProgressMeter - chr2:36195824 2.48956422E8 4.2 h 60.0 s 8.9% 47.1 h 42.9 h
INFO 14:51:23,164 ProgressMeter - chr2:37600017 2.48956422E8 4.2 h 60.0 s 8.9% 47.1 h 42.9 h
INFO 14:52:23,165 ProgressMeter - chr2:38791413 2.48956422E8 4.2 h 60.0 s 8.9% 47.1 h 42.8 h

ERROR --

ERROR stack trace

java.util.NoSuchElementException
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1431)
at java.util.HashMap$KeyIterator.next(HashMap.java:1453)
at org.broadinstitute.gatk.tools.walkers.haplotypecaller.HaplotypeCallerGenotypingEngine.reduceNumberOfAlternativeAllelesBasedOnLikelihoods(HaplotypeCallerGenotypingEngine.java:336)
at org.broadinstitute.gatk.tools.walkers.haplotypecaller.HaplotypeCallerGenotypingEngine.assignGenotypeLikelihoods(HaplotypeCallerGenotypingEngine.java:264)
at org.broadinstitute.gatk.tools.walkers.haplotypecaller.HaplotypeCaller.map(HaplotypeCaller.java:964)
at org.broadinstitute.gatk.tools.walkers.haplotypecaller.HaplotypeCaller.map(HaplotypeCaller.java:251)
at org.broadinstitute.gatk.engine.traversals.TraverseActiveRegions$TraverseActiveRegionMap.apply(TraverseActiveRegions.java:709)
at org.broadinstitute.gatk.engine.traversals.TraverseActiveRegions$TraverseActiveRegionMap.apply(TraverseActiveRegions.java:705)
at org.broadinstitute.gatk.utils.nanoScheduler.NanoScheduler.executeSingleThreaded(NanoScheduler.java:274)
at org.broadinstitute.gatk.utils.nanoScheduler.NanoScheduler.execute(NanoScheduler.java:245)
at org.broadinstitute.gatk.engine.traversals.TraverseActiveRegions.traverse(TraverseActiveRegions.java:274)
at org.broadinstitute.gatk.engine.traversals.TraverseActiveRegions.traverse(TraverseActiveRegions.java:78)
at org.broadinstitute.gatk.engine.executive.LinearMicroScheduler.execute(LinearMicroScheduler.java:99)
at org.broadinstitute.gatk.engine.GenomeAnalysisEngine.execute(GenomeAnalysisEngine.java:311)
at org.broadinstitute.gatk.engine.CommandLineExecutable.execute(CommandLineExecutable.java:113)
at org.broadinstitute.gatk.utils.commandline.CommandLineProgram.start(CommandLineProgram.java:255)
at org.broadinstitute.gatk.utils.commandline.CommandLineProgram.start(CommandLineProgram.java:157)
at org.broadinstitute.gatk.engine.CommandLineGATK.main(CommandLineGATK.java:108)

ERROR ------------------------------------------------------------------------------------------

ERROR A GATK RUNTIME ERROR has occurred (version 3.6-0-g89b7209):

ERROR

ERROR This might be a bug. Please check the documentation guide to see if this is a known problem.

ERROR If not, please post the error message, with stack trace, to the GATK forum.

ERROR Visit our website and forum for extensive documentation and answers to

ERROR commonly asked questions https://www.broadinstitute.org/gatk

ERROR

ERROR MESSAGE: Code exception (see stack trace for error itself)

ERROR ------------------------------------------------------------------------------------------