AWS Cloudformation CLI uses shorthand syntax when passing parameters as json file

I am trying to run the following command:

aws cloudformation update-stack --stack-name $stack.Trim('"') --use-previous-template --parameters file://./parameters.json

This is the content of parameters.json (you can copy and paste here to check it is a valid JSON string):

[{"ParameterKey":"directoryName","UsePreviousValue":true},{"ParameterKey":"CodeDeployServiceRole","UsePreviousValue":true},{"ParameterKey":"ApplicationType","UsePreviousValue":true},{"ParameterKey":"EnvironmentCode","UsePreviousValue":true},{"ParameterKey":"InstanceRoleInstanceProfile","UsePreviousValue":true},{"ParameterKey":"VPCID","UsePreviousValue":true},{"ParameterKey":"SecurityGroupList","UsePreviousValue":true},{"ParameterKey":"KeyName","UsePreviousValue":true},{"ParameterKey":"Subnets","UsePreviousValue":true},{"ParameterKey":"dnsIpAddresses","UsePreviousValue":true},{"ParameterKey":"directoryId","UsePreviousValue":true},{"ParameterKey":"directoryBIOS","UsePreviousValue":true},{"ParameterKey":"ScalingTermination","UsePreviousValue":true},{"ParameterKey":"EC2ScaleUpCooldown","UsePreviousValue":true},{"ParameterKey":"AttributeDelayTimeout","UsePreviousValue":true},{"ParameterKey":"CwLowOperator","UsePreviousValue":true},{"ParameterKey":"EBSOptimized","UsePreviousValue":true},{"ParameterKey":"PatchingGroupTag","UsePreviousValue":true},{"ParameterKey":"CwHighOperator","UsePreviousValue":true},{"ParameterKey":"SSMInventoryTag","UsePreviousValue":true},{"ParameterKey":"CwHighEvaluations","UsePreviousValue":true},{"ParameterKey":"EC2ScaleUpAdjustment","UsePreviousValue":true},{"ParameterKey":"CwScalingMetric","UsePreviousValue":true},{"ParameterKey":"HealthyThresholdCount","UsePreviousValue":true},{"ParameterKey":"ImageId","ParameterValue":"ami-0b2e03736f1241bbb"},{"ParameterKey":"CodeDeployServiceRole","UsePreviousValue":true},{"ParameterKey":"directoryName","UsePreviousValue":true},{"ParameterKey":"HealthCheckIntervalSeconds","UsePreviousValue":true},{"ParameterKey":"ReleaseId","UsePreviousValue":true},{"ParameterKey":"UnhealthyThresholdCount","UsePreviousValue":true},{"ParameterKey":"EC2ScaleDownAdjustment","UsePreviousValue":true},{"ParameterKey":"ApplicationType","UsePreviousValue":true},{"ParameterKey":"EnvironmentCode","UsePreviousValue":true},{"ParameterKey":"Environment","UsePreviousValue":true},{"ParameterKey":"EbsVolumeType","UsePreviousValue":true},{"ParameterKey":"BackupsEnabled","UsePreviousValue":true},{"ParameterKey":"CwLowPeriod","UsePreviousValue":true},{"ParameterKey":"HealthCheckType","UsePreviousValue":true},{"ParameterKey":"InstanceRoleInstanceProfile","UsePreviousValue":true},{"ParameterKey":"ServiceLevel","UsePreviousValue":true},{"ParameterKey":"TerminatedInstances","UsePreviousValue":true},{"ParameterKey":"VPCID","UsePreviousValue":true},{"ParameterKey":"HealthCheckPath","UsePreviousValue":true},{"ParameterKey":"CwHighPeriod","UsePreviousValue":true},{"ParameterKey":"HealthCheckGracePeriod","UsePreviousValue":true},{"ParameterKey":"HealthCheckTimeoutSeconds","UsePreviousValue":true},{"ParameterKey":"CustomCWConfig","UsePreviousValue":true},{"ParameterKey":"ScalingMin","UsePreviousValue":true},{"ParameterKey":"SecurityGroupList","UsePreviousValue":true},{"ParameterKey":"CwLowEvaluations","UsePreviousValue":true},{"ParameterKey":"directoryBIOS","UsePreviousValue":true},{"ParameterKey":"CustomSSMStepCount","UsePreviousValue":true},{"ParameterKey":"ScalingMax","UsePreviousValue":true},{"ParameterKey":"InstanceType","UsePreviousValue":true},{"ParameterKey":"EncryptEBSVolume","UsePreviousValue":true},{"ParameterKey":"SSMRefreshFrequency","UsePreviousValue":true},{"ParameterKey":"CwHighThreshold","UsePreviousValue":true},{"ParameterKey":"CustomSSMSteps","UsePreviousValue":true},{"ParameterKey":"MinInstancesInService","UsePreviousValue":true},{"ParameterKey":"MatcherCode","UsePreviousValue":true},{"ParameterKey":"EbsVolumeSize","UsePreviousValue":true},{"ParameterKey":"EC2ScaleDownCooldown","UsePreviousValue":true},{"ParameterKey":"Iops","UsePreviousValue":true},{"ParameterKey":"KeyName","UsePreviousValue":true},{"ParameterKey":"Subnets","UsePreviousValue":true},{"ParameterKey":"dnsIpAddresses","UsePreviousValue":true},{"ParameterKey":"CWLogRetention","UsePreviousValue":true},{"ParameterKey":"EnableRackspaceTicket","UsePreviousValue":true},{"ParameterKey":"CwLowThreshold","UsePreviousValue":true},{"ParameterKey":"directoryId","UsePreviousValue":true},{"ParameterKey":"ScalingNotificationTopic","UsePreviousValue":true},{"ParameterKey":"LoadBalancerFullName","UsePreviousValue":true}]

I get this when I run the command:

aws : 
At line:1 char:1
+ aws cloudformation update-stack --stack-name $stack.Trim('"') --templ ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

Error parsing parameter '--parameters': Expected: '=', received: 'ÿ' for input:
ÿþ[ { " P a r a m e t e r K e y " : " d i r e c t o r y N a m e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C o d e D e p l o y S e r v i c e R o l e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r
 a m e t e r K e y " : " A p p l i c a t i o n T y p e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E n v i r o n m e n t C o d e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " 
: " I n s t a n c e R o l e I n s t a n c e P r o f i l e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " V P C I D " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S e c u r i t
 y G r o u p L i s t " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " K e y N a m e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S u b n e t s " , " U s e P r e v i o u s V a 
l u e " : t r u e } , { " P a r a m e t e r K e y " : " d n s I p A d d r e s s e s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " d i r e c t o r y I d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r
 a m e t e r K e y " : " d i r e c t o r y B I O S " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S c a l i n g T e r m i n a t i o n " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y 
" : " E C 2 S c a l e U p C o o l d o w n " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " A t t r i b u t e D e l a y T i m e o u t " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " :
 " C w L o w O p e r a t o r " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E B S O p t i m i z e d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " P a t c h i n g G r o u p T 
a g " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w H i g h O p e r a t o r " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S S M I n v e n t o r y T a g " , " U s e P r e v
 i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w H i g h E v a l u a t i o n s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E C 2 S c a l e U p A d j u s t m e n t " , " U s e P r e v i o u 
s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w S c a l i n g M e t r i c " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " H e a l t h y T h r e s h o l d C o u n t " , " U s e P r e v i o u s V a l u
 e " : t r u e } , { " P a r a m e t e r K e y " : " I m a g e I d " , " P a r a m e t e r V a l u e " : " a m i - 0 b 2 e 0 3 7 3 6 f 1 2 4 1 b b b " } , { " P a r a m e t e r K e y " : " C o d e D e p l o y S e r v i c e R o l e " , " U s e P r e v i o u 
s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " d i r e c t o r y N a m e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " H e a l t h C h e c k I n t e r v a l S e c o n d s " , " U s e P r e v i o u s V
 a l u e " : t r u e } , { " P a r a m e t e r K e y " : " R e l e a s e I d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " U n h e a l t h y T h r e s h o l d C o u n t " , " U s e P r e v i o u s V a l u e " : t r 
u e } , { " P a r a m e t e r K e y " : " E C 2 S c a l e D o w n A d j u s t m e n t " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " A p p l i c a t i o n T y p e " , " U s e P r e v i o u s V a l u e " : t r u e } ,
 { " P a r a m e t e r K e y " : " E n v i r o n m e n t C o d e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E n v i
 r o n m e n t " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E b s V o l u m e T y p e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " B a c k u p s E n a b l e d " , " U s e 
P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w L o w P e r i o d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " H e a l t h C h e c k T y p e " , " U s e P r e v i o u s V a l u e " :
 t r u e } , { " P a r a m e t e r K e y " : " I n s t a n c e R o l e I n s t a n c e P r o f i l e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S e r v i c e L e v e l " , " U s e P r e v i o u s V a l u e " : t 
r u e } , { " P a r a m e t e r K e y " : " T e r m i n a t e d I n s t a n c e s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " V P C I D " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K
 e y " : " H e a l t h C h e c k P a t h " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w H i g h P e r i o d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " H e a l t h C h 
e c k G r a c e P e r i o d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " H e a l t h C h e c k T i m e o u t S e c o n d s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C u
 s t o m C W C o n f i g " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S c a l i n g M i n " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S e c u r i t y G r o u p L i s t " 
, " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w L o w E v a l u a t i o n s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " d i r e c t o r y B I O S " , " U s e P r e v i o u
 s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C u s t o m S S M S t e p C o u n t " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S c a l i n g M a x " , " U s e P r e v i o u s V a l u e " : t r u e 
} , { " P a r a m e t e r K e y " : " I n s t a n c e T y p e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E n c r y p t E B S V o l u m e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r
 K e y " : " S S M R e f r e s h F r e q u e n c y " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w H i g h T h r e s h o l d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " 
C u s t o m S S M S t e p s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " M i n I n s t a n c e s I n S e r v i c e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " M a t c h e
 r C o d e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E b s V o l u m e S i z e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E C 2 S c a l e D o w n C o o l d o w n " , 
" U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " I o p s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " K e y N a m e " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r
 a m e t e r K e y " : " S u b n e t s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " d n s I p A d d r e s s e s " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C W L o g R e 
t e n t i o n " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " E n a b l e R a c k s p a c e T i c k e t " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " C w L o w
 T h r e s h o l d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " d i r e c t o r y I d " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " S c a l i n g N o t i f i c a t i o n T 
o p i c " , " U s e P r e v i o u s V a l u e " : t r u e } , { " P a r a m e t e r K e y " : " L o a d B a l a n c e r F u l l N a m e " , " U s e P r e v i o u s V a l u e " : t r u e } ] 
^

I have run the command using --debug and noticed that it tries to parse the parameters using shorthand syntax:

2019-04-15 14:11:36,069 - MainThread - botocore.hooks - DEBUG - Event process-cli-arg.cloudformation.update-stack: calling handler <awscli.argprocess.ParamShorthandParser object at 0x0000020212160F28>
2019-04-15 14:11:36,070 - MainThread - awscli.argprocess - DEBUG - Parsing param --parameters as shorthand

I cannot find any way to force the CLI to parse the parameters using JSON syntax rather than shorthand. From the docs, it looks like it should do that automatically.

Any ideas why it tries to use the shorthand syntax?