I am running CombineGVCFs to integrate two raw_variants.vcf files derived from HaplotypeCaller, it throws an error as below. GATK version is v4.1.8.1. Any suggestions for this?

10:31:33.609 INFO  NativeLibraryLoader - Loading libgkl_compression.so from jar:file:/ubda/home/19044464r/biosoft/gatk-4.1.8.1/gatk-package-4.1.8.1-local.jar!/com/intel/gkl/native/libgkl_compression.so
Mar 21, 2022 10:31:33 AM shaded.cloud_nio.com.google.auth.oauth2.ComputeEngineCredentials runningOnComputeEngine
INFO: Failed to detect whether we are running on Google Compute Engine.
10:31:33.977 INFO  CombineGVCFs - ------------------------------------------------------------
10:31:33.977 INFO  CombineGVCFs - The Genome Analysis Toolkit (GATK) v4.1.8.1
10:31:33.977 INFO  CombineGVCFs - For support and documentation go to https://software.broadinstitute.org/gatk/
10:31:33.978 INFO  CombineGVCFs - Executing as 19044464r@ubda-d049 on Linux v3.10.0-693.21.1.el7.x86_64 amd64
10:31:33.978 INFO  CombineGVCFs - Java runtime: OpenJDK 64-Bit Server VM v1.8.0_252-b09
10:31:33.978 INFO  CombineGVCFs - Start Date/Time: March 21, 2022 10:31:33 AM HKT
10:31:33.978 INFO  CombineGVCFs - ------------------------------------------------------------
10:31:33.978 INFO  CombineGVCFs - ------------------------------------------------------------
10:31:33.979 INFO  CombineGVCFs - HTSJDK Version: 2.23.0
10:31:33.979 INFO  CombineGVCFs - Picard Version: 2.22.8
10:31:33.979 INFO  CombineGVCFs - HTSJDK Defaults.COMPRESSION_LEVEL : 2
10:31:33.979 INFO  CombineGVCFs - HTSJDK Defaults.USE_ASYNC_IO_READ_FOR_SAMTOOLS : false
10:31:33.980 INFO  CombineGVCFs - HTSJDK Defaults.USE_ASYNC_IO_WRITE_FOR_SAMTOOLS : true
10:31:33.980 INFO  CombineGVCFs - HTSJDK Defaults.USE_ASYNC_IO_WRITE_FOR_TRIBBLE : false
10:31:33.980 INFO  CombineGVCFs - Deflater: IntelDeflater
10:31:33.980 INFO  CombineGVCFs - Inflater: IntelInflater
10:31:33.980 INFO  CombineGVCFs - GCS max retries/reopens: 20
10:31:33.980 INFO  CombineGVCFs - Requester pays: disabled
10:31:33.981 INFO  CombineGVCFs - Initializing engine
10:31:34.825 INFO  FeatureManager - Using codec VCFCodec to read file file:///ubda/home/19044464r/project/CNV-calling/analysis/test2/1-29406_raw_variants.vcf
10:31:35.333 INFO  FeatureManager - Using codec VCFCodec to read file file:///ubda/home/19044464r/project/CNV-calling/analysis/test2/1-29683_raw_variants.vcf
10:31:35.971 INFO  CombineGVCFs - Done initializing engine
10:31:36.044 INFO  ProgressMeter - Starting traversal
10:31:36.045 INFO  ProgressMeter -        Current Locus  Elapsed Minutes    Variants Processed  Variants/Minute
10:31:36.276 INFO  CombineGVCFs - Shutting down engine
[March 21, 2022 10:31:36 AM HKT] org.broadinstitute.hellbender.tools.walkers.CombineGVCFs done. Elapsed time: 0.05 minutes.
Runtime.totalMemory()=2060451840
java.lang.IllegalStateException: Key END found in VariantContext field INFO at chr1:20094 but this key isn't defined in the VCFHeader.  We require all VCFs to have complete VCF headers by default.
        at htsjdk.variant.vcf.VCFEncoder.fieldIsMissingFromHeaderError(VCFEncoder.java:213)
        at htsjdk.variant.vcf.VCFEncoder.write(VCFEncoder.java:146)
        at htsjdk.variant.variantcontext.writer.VCFWriter.add(VCFWriter.java:250)
        at org.broadinstitute.hellbender.tools.walkers.CombineGVCFs.endPreviousStates(CombineGVCFs.java:408)
        at org.broadinstitute.hellbender.tools.walkers.CombineGVCFs.createIntermediateVariants(CombineGVCFs.java:217)
        at org.broadinstitute.hellbender.tools.walkers.CombineGVCFs.apply(CombineGVCFs.java:162)
        at org.broadinstitute.hellbender.engine.MultiVariantWalkerGroupedOnStart.apply(MultiVariantWalkerGroupedOnStart.java:131)
        at org.broadinstitute.hellbender.engine.MultiVariantWalkerGroupedOnStart.apply(MultiVariantWalkerGroupedOnStart.java:106)
        at org.broadinstitute.hellbender.engine.MultiVariantWalker.lambda$traverse$1(MultiVariantWalker.java:120)
        at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
        at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
        at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
        at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
         at java.util.Iterator.forEachRemaining(Iterator.java:116)
        at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
        at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
        at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:485)
        at org.broadinstitute.hellbender.engine.MultiVariantWalker.traverse(MultiVariantWalker.java:118)
        at org.broadinstitute.hellbender.engine.MultiVariantWalkerGroupedOnStart.traverse(MultiVariantWalkerGroupedOnStart.java:163)
        at org.broadinstitute.hellbender.engine.GATKTool.doWork(GATKTool.java:1049)
        at org.broadinstitute.hellbender.cmdline.CommandLineProgram.runTool(CommandLineProgram.java:140)
        at org.broadinstitute.hellbender.cmdline.CommandLineProgram.instanceMainPostParseArgs(CommandLineProgram.java:192)
        at org.broadinstitute.hellbender.cmdline.CommandLineProgram.instanceMain(CommandLineProgram.java:211)
        at org.broadinstitute.hellbender.Main.runCommandLineProgram(Main.java:160)
        at org.broadinstitute.hellbender.Main.mainEntry(Main.java:203)
        at org.broadinstitute.hellbender.Main.main(Main.java:289)
Using GATK jar /ubda/home/19044464r/biosoft/gatk-4.1.8.1/gatk-package-4.1.8.1-local.jar
Running:
    java -Dsamjdk.use_async_io_read_samtools=false -Dsamjdk.use_async_io_write_samtools=true -Dsamjdk.use_async_io_write_tribble=false -Dsamjdk.compression_level=2 -Xmx30G -jar /ubda/home/19044464r/biosoft/gatk-4.1.8.1/gatk-package-4.1.8.1-local.jar CombineGVCFs -R /ubda/home/19044464r/refs/hg38/ucsc-fasta/hg38.analysisSet.fa -V 1-29406_raw_variants.vcf -V 1-29683_raw_variants.vcf -O cohort.g.vcf.gz