I have looked through many of the forum posts but just can't put my finger on what the Discount__c field has to do with Step #4.

I get the following error followed by an email:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_EXECUTE_FLOW_TRIGGER, The record couldn’t be saved because it failed to trigger a flow. A flow trigger failed to execute the flow with version ID 3011I000000PJU7. Flow error messages: An unhandled fault has occurred in this flow
An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information. Contact your administrator for help.: []

the email:

Error element myRule_1_A1 (FlowRecordCreate).
This error occurred when the flow tried to create records: REQUIRED_FIELD_MISSING: Required fields are missing: [Discount__c]. For details, see API Exceptions.
This report lists the elements that the flow interview executed. The report is a beta feature.
We welcome your feedback on IdeaExchange.
Flow Details
Flow Name: Fulfillment_Creation
Type: Workflow
Version: 4
Status: Active
Flow Interview Details
Interview Label: Fulfillment_Creation-4_InterviewLabel
Current User: Jeroen van den Eijkhof (0051I000000qFJl)
Start time: 10/3/2017 7:55 PM
Duration: 0 seconds
How the Interview Started
Jeroen van den Eijkhof (0051I000000qFJl) started the flow interview.
Some of this flow's variables were set when the interview started.
myVariable_old = null
myVariable_current = 00k1I00000AepL1QAJ
ASSIGNMENT: myVariable_waitStartTimeAssignment
{!myVariable_waitStartTimeVariable} Equals {!Flow.CurrentDateTime}
Result
{!myVariable_waitStartTimeVariable} = "10/3/2017 7:55 PM"
DECISION: myPreWaitDecision_myWait_myRule_1
Executed this outcome: myPreWaitRule_myWait_myRule_1
Outcome conditions: and
1. {!myVariable_current.Opportunity.StageName} (New) Does not equal Cancelled
2. {!myVariable_current.Fulfillment_Created__c} (false) Equals false
Logic: All conditions must be true (AND)
DECISION: myDecision
Executed this outcome: myRule_1
Outcome conditions: and
1. {!myVariable_current.Opportunity.StageName} (New) Does not equal Cancelled
2. {!myVariable_current.Fulfillment_Created__c} (false) Equals false
Logic: All conditions must be true (AND)
RECORD CREATE: myRule_1_A1
Create one Fulfillment__c record where:
AdventurePackageId__c = {!myVariable_current.Id} (00k1I00000AepL1QAJ)
Adventure_Package_Cost__c = {!myVariable_current.TotalPrice} (1)
Adventure__c = {!myVariable_current.Product2Id} (01t1I000000IoClQAK)
Expedition_Leader__c = {!myVariable_current.Product2.Expedition_Leader__c} (null)
Explorer__c = {!myVariable_current.Explorer__c} (0031I000002pnbsQAA)
Name = {!formula_2_myRule_1_A1_8225086771} (Lemons00k1I00000AepL1QAJ)
Opportunity__c = {!myVariable_current.OpportunityId} (0061I000002RhpDQAS)
Schedule_Date__c = {!myVariable_current.ServiceDate} (January 1, 2050)
Status__c = New
Result
Failed to create record.

Error Occurred: This error occurred when the flow tried to create records: REQUIRED_FIELD_MISSING: Required fields are missing: [Discount__c]. For details, see API Exceptions.

I have the Discount_c field on the Opportunity object and it is set to required as well as defaulted to 0.
Your help is appreciated!

I am getting the below error on the "Process Automation - Automate Basic Business Processes with Process Builder" step:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_EXECUTE_FLOW_TRIGGER, The record couldn’t be saved because it failed to trigger a flow. A flow trigger failed to execute the flow with version ID 3011I000000GuHH. Flow error messages: An unhandled fault has occurred in this flow
An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information. Contact your administrator for help.: []

Based on this error I got a corresponding email:

Error element myRule_1_A1 (FlowRecordUpdate).
This error occurred when the flow tried to update records: The flow failed to access the value for myVariable_current.Parent.ShippingCity because it hasn't been set or assigned.. For details, see API Exceptions.
This report lists the elements that the flow interview executed. The report is a beta feature.
We welcome your feedback on IdeaExchange.
Flow Details
Flow Name: DoItNow
Type: Workflow
Version: 4
Status: Active
Flow Interview Details
Interview Label: DoItNow-4_InterviewLabel
Current User: Jeroen van den Eijkhof (0051I000000RCeg)
Start time: 9/26/2017 1:37 PM
Duration: 0 seconds
How the Interview Started
Jeroen van den Eijkhof (0051I000000RCeg) started the flow interview.
Some of this flow's variables were set when the interview started.
myVariable_old = 0011I00000330LWQAY
myVariable_current = 0011I00000330LWQAY
ASSIGNMENT: myVariable_waitStartTimeAssignment
{!myVariable_waitStartTimeVariable} Equals {!Flow.CurrentDateTime}
Result
{!myVariable_waitStartTimeVariable} = "9/26/2017 1:37 PM"
DECISION: isChangedDecision2_myRule_1_ShippingCity
Executed this outcome: isChangedRule_2_myRule_1_ShippingCity
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingCity} (null) Does not equal {!myVariable_current.ShippingCity} (Staines)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision3_myRule_1_ShippingCountry
Executed this outcome: isChangedRule_3_myRule_1_ShippingCountry
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingCountry} (null) Does not equal {!myVariable_current.ShippingCountry} (UK)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision4_myRule_1_ShippingStreet
Executed this outcome: isChangedRule_4_myRule_1_ShippingStreet
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingStreet} (null) Does not equal {!myVariable_current.ShippingStreet} (1 Street)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision5_myRule_1_ShippingState
Executed this outcome: isChangedRule_5_myRule_1_ShippingState
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingState} (null) Does not equal {!myVariable_current.ShippingState} (Middlesex)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision6_myRule_1_ShippingPostalCode
Executed this outcome: isChangedRule_6_myRule_1_ShippingPostalCode
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingPostalCode} (null) Does not equal {!myVariable_current.ShippingPostalCode} (TW18 3AG)
Logic: All conditions must be true (AND)

DECISION: myDecision
Executed this outcome: myRule_1
Outcome conditions: or
1. {!isChangedRule_2_myRule_1_ShippingCity} (true) Equals true
2. {!isChangedRule_3_myRule_1_ShippingCountry} (true) Equals true
3. {!isChangedRule_4_myRule_1_ShippingStreet} (true) Equals true
4. {!isChangedRule_5_myRule_1_ShippingState} (true) Equals true
5. {!isChangedRule_6_myRule_1_ShippingPostalCode} (true) Equals true
Logic: One condition must be true (OR)

RECORD UPDATE: myRule_1_A1
Find all Contact records where:
AccountId Equals {!myVariable_current.Id} (0011I00000330LWQAY)
Update the records’ field values.
MailingCity = {!myVariable_current.Parent.ShippingCity} (<interaction.engine.info.GenericInterviewValueKey@6c35937b couldn't be resolved>)
MailingCountry = {!myVariable_current.Parent.ShippingCountry} (<interaction.engine.info.GenericInterviewValueKey@7e65001a couldn't be resolved>)
MailingPostalCode = {!myVariable_current.Parent.ShippingPostalCode} (<interaction.engine.info.GenericInterviewValueKey@5f07b547 couldn't be resolved>)
MailingState = {!myVariable_current.Parent.ShippingState} (<interaction.engine.info.GenericInterviewValueKey@5b3e388e couldn't be resolved>)
MailingStreet = {!myVariable_current.Parent.ShippingStreet} (<interaction.engine.info.GenericInterviewValueKey@3865f33a couldn't be resolved>)
Result
Failed to update records that meet the filter criteria.

Error Occurred: The flow failed to access the value for myVariable_current.Parent.ShippingCity because it hasn't been set or assigned.

Any help is appreciated
 

I have looked through many of the forum posts but just can't put my finger on what the Discount__c field has to do with Step #4.

I get the following error followed by an email:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_EXECUTE_FLOW_TRIGGER, The record couldn’t be saved because it failed to trigger a flow. A flow trigger failed to execute the flow with version ID 3011I000000PJU7. Flow error messages: An unhandled fault has occurred in this flow
An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information. Contact your administrator for help.: []

the email:

Error element myRule_1_A1 (FlowRecordCreate).
This error occurred when the flow tried to create records: REQUIRED_FIELD_MISSING: Required fields are missing: [Discount__c]. For details, see API Exceptions.
This report lists the elements that the flow interview executed. The report is a beta feature.
We welcome your feedback on IdeaExchange.
Flow Details
Flow Name: Fulfillment_Creation
Type: Workflow
Version: 4
Status: Active
Flow Interview Details
Interview Label: Fulfillment_Creation-4_InterviewLabel
Current User: Jeroen van den Eijkhof (0051I000000qFJl)
Start time: 10/3/2017 7:55 PM
Duration: 0 seconds
How the Interview Started
Jeroen van den Eijkhof (0051I000000qFJl) started the flow interview.
Some of this flow's variables were set when the interview started.
myVariable_old = null
myVariable_current = 00k1I00000AepL1QAJ
ASSIGNMENT: myVariable_waitStartTimeAssignment
{!myVariable_waitStartTimeVariable} Equals {!Flow.CurrentDateTime}
Result
{!myVariable_waitStartTimeVariable} = "10/3/2017 7:55 PM"
DECISION: myPreWaitDecision_myWait_myRule_1
Executed this outcome: myPreWaitRule_myWait_myRule_1
Outcome conditions: and
1. {!myVariable_current.Opportunity.StageName} (New) Does not equal Cancelled
2. {!myVariable_current.Fulfillment_Created__c} (false) Equals false
Logic: All conditions must be true (AND)
DECISION: myDecision
Executed this outcome: myRule_1
Outcome conditions: and
1. {!myVariable_current.Opportunity.StageName} (New) Does not equal Cancelled
2. {!myVariable_current.Fulfillment_Created__c} (false) Equals false
Logic: All conditions must be true (AND)
RECORD CREATE: myRule_1_A1
Create one Fulfillment__c record where:
AdventurePackageId__c = {!myVariable_current.Id} (00k1I00000AepL1QAJ)
Adventure_Package_Cost__c = {!myVariable_current.TotalPrice} (1)
Adventure__c = {!myVariable_current.Product2Id} (01t1I000000IoClQAK)
Expedition_Leader__c = {!myVariable_current.Product2.Expedition_Leader__c} (null)
Explorer__c = {!myVariable_current.Explorer__c} (0031I000002pnbsQAA)
Name = {!formula_2_myRule_1_A1_8225086771} (Lemons00k1I00000AepL1QAJ)
Opportunity__c = {!myVariable_current.OpportunityId} (0061I000002RhpDQAS)
Schedule_Date__c = {!myVariable_current.ServiceDate} (January 1, 2050)
Status__c = New
Result
Failed to create record.

Error Occurred: This error occurred when the flow tried to create records: REQUIRED_FIELD_MISSING: Required fields are missing: [Discount__c]. For details, see API Exceptions.

I have the Discount_c field on the Opportunity object and it is set to required as well as defaulted to 0.
Your help is appreciated!

I have looked through many of the forum posts but just can't put my finger on what the Discount__c field has to do with Step #4.

I get the following error followed by an email:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_EXECUTE_FLOW_TRIGGER, The record couldn’t be saved because it failed to trigger a flow. A flow trigger failed to execute the flow with version ID 3011I000000PJU7. Flow error messages: An unhandled fault has occurred in this flow
An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information. Contact your administrator for help.: []

the email:

Error element myRule_1_A1 (FlowRecordCreate).
This error occurred when the flow tried to create records: REQUIRED_FIELD_MISSING: Required fields are missing: [Discount__c]. For details, see API Exceptions.
This report lists the elements that the flow interview executed. The report is a beta feature.
We welcome your feedback on IdeaExchange.
Flow Details
Flow Name: Fulfillment_Creation
Type: Workflow
Version: 4
Status: Active
Flow Interview Details
Interview Label: Fulfillment_Creation-4_InterviewLabel
Current User: Jeroen van den Eijkhof (0051I000000qFJl)
Start time: 10/3/2017 7:55 PM
Duration: 0 seconds
How the Interview Started
Jeroen van den Eijkhof (0051I000000qFJl) started the flow interview.
Some of this flow's variables were set when the interview started.
myVariable_old = null
myVariable_current = 00k1I00000AepL1QAJ
ASSIGNMENT: myVariable_waitStartTimeAssignment
{!myVariable_waitStartTimeVariable} Equals {!Flow.CurrentDateTime}
Result
{!myVariable_waitStartTimeVariable} = "10/3/2017 7:55 PM"
DECISION: myPreWaitDecision_myWait_myRule_1
Executed this outcome: myPreWaitRule_myWait_myRule_1
Outcome conditions: and
1. {!myVariable_current.Opportunity.StageName} (New) Does not equal Cancelled
2. {!myVariable_current.Fulfillment_Created__c} (false) Equals false
Logic: All conditions must be true (AND)
DECISION: myDecision
Executed this outcome: myRule_1
Outcome conditions: and
1. {!myVariable_current.Opportunity.StageName} (New) Does not equal Cancelled
2. {!myVariable_current.Fulfillment_Created__c} (false) Equals false
Logic: All conditions must be true (AND)
RECORD CREATE: myRule_1_A1
Create one Fulfillment__c record where:
AdventurePackageId__c = {!myVariable_current.Id} (00k1I00000AepL1QAJ)
Adventure_Package_Cost__c = {!myVariable_current.TotalPrice} (1)
Adventure__c = {!myVariable_current.Product2Id} (01t1I000000IoClQAK)
Expedition_Leader__c = {!myVariable_current.Product2.Expedition_Leader__c} (null)
Explorer__c = {!myVariable_current.Explorer__c} (0031I000002pnbsQAA)
Name = {!formula_2_myRule_1_A1_8225086771} (Lemons00k1I00000AepL1QAJ)
Opportunity__c = {!myVariable_current.OpportunityId} (0061I000002RhpDQAS)
Schedule_Date__c = {!myVariable_current.ServiceDate} (January 1, 2050)
Status__c = New
Result
Failed to create record.

Error Occurred: This error occurred when the flow tried to create records: REQUIRED_FIELD_MISSING: Required fields are missing: [Discount__c]. For details, see API Exceptions.

I have the Discount_c field on the Opportunity object and it is set to required as well as defaulted to 0.
Your help is appreciated!

I am getting the below error on the "Process Automation - Automate Basic Business Processes with Process Builder" step:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_EXECUTE_FLOW_TRIGGER, The record couldn’t be saved because it failed to trigger a flow. A flow trigger failed to execute the flow with version ID 3011I000000GuHH. Flow error messages: An unhandled fault has occurred in this flow
An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information. Contact your administrator for help.: []

Based on this error I got a corresponding email:

Error element myRule_1_A1 (FlowRecordUpdate).
This error occurred when the flow tried to update records: The flow failed to access the value for myVariable_current.Parent.ShippingCity because it hasn't been set or assigned.. For details, see API Exceptions.
This report lists the elements that the flow interview executed. The report is a beta feature.
We welcome your feedback on IdeaExchange.
Flow Details
Flow Name: DoItNow
Type: Workflow
Version: 4
Status: Active
Flow Interview Details
Interview Label: DoItNow-4_InterviewLabel
Current User: Jeroen van den Eijkhof (0051I000000RCeg)
Start time: 9/26/2017 1:37 PM
Duration: 0 seconds
How the Interview Started
Jeroen van den Eijkhof (0051I000000RCeg) started the flow interview.
Some of this flow's variables were set when the interview started.
myVariable_old = 0011I00000330LWQAY
myVariable_current = 0011I00000330LWQAY
ASSIGNMENT: myVariable_waitStartTimeAssignment
{!myVariable_waitStartTimeVariable} Equals {!Flow.CurrentDateTime}
Result
{!myVariable_waitStartTimeVariable} = "9/26/2017 1:37 PM"
DECISION: isChangedDecision2_myRule_1_ShippingCity
Executed this outcome: isChangedRule_2_myRule_1_ShippingCity
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingCity} (null) Does not equal {!myVariable_current.ShippingCity} (Staines)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision3_myRule_1_ShippingCountry
Executed this outcome: isChangedRule_3_myRule_1_ShippingCountry
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingCountry} (null) Does not equal {!myVariable_current.ShippingCountry} (UK)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision4_myRule_1_ShippingStreet
Executed this outcome: isChangedRule_4_myRule_1_ShippingStreet
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingStreet} (null) Does not equal {!myVariable_current.ShippingStreet} (1 Street)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision5_myRule_1_ShippingState
Executed this outcome: isChangedRule_5_myRule_1_ShippingState
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingState} (null) Does not equal {!myVariable_current.ShippingState} (Middlesex)
Logic: All conditions must be true (AND)

DECISION: isChangedDecision6_myRule_1_ShippingPostalCode
Executed this outcome: isChangedRule_6_myRule_1_ShippingPostalCode
Outcome conditions: and
1. {!myVariable_old} (0011I00000330LWQAY) Is null false
2. {!myVariable_old.ShippingPostalCode} (null) Does not equal {!myVariable_current.ShippingPostalCode} (TW18 3AG)
Logic: All conditions must be true (AND)

DECISION: myDecision
Executed this outcome: myRule_1
Outcome conditions: or
1. {!isChangedRule_2_myRule_1_ShippingCity} (true) Equals true
2. {!isChangedRule_3_myRule_1_ShippingCountry} (true) Equals true
3. {!isChangedRule_4_myRule_1_ShippingStreet} (true) Equals true
4. {!isChangedRule_5_myRule_1_ShippingState} (true) Equals true
5. {!isChangedRule_6_myRule_1_ShippingPostalCode} (true) Equals true
Logic: One condition must be true (OR)

RECORD UPDATE: myRule_1_A1
Find all Contact records where:
AccountId Equals {!myVariable_current.Id} (0011I00000330LWQAY)
Update the records’ field values.
MailingCity = {!myVariable_current.Parent.ShippingCity} (<interaction.engine.info.GenericInterviewValueKey@6c35937b couldn't be resolved>)
MailingCountry = {!myVariable_current.Parent.ShippingCountry} (<interaction.engine.info.GenericInterviewValueKey@7e65001a couldn't be resolved>)
MailingPostalCode = {!myVariable_current.Parent.ShippingPostalCode} (<interaction.engine.info.GenericInterviewValueKey@5f07b547 couldn't be resolved>)
MailingState = {!myVariable_current.Parent.ShippingState} (<interaction.engine.info.GenericInterviewValueKey@5b3e388e couldn't be resolved>)
MailingStreet = {!myVariable_current.Parent.ShippingStreet} (<interaction.engine.info.GenericInterviewValueKey@3865f33a couldn't be resolved>)
Result
Failed to update records that meet the filter criteria.

Error Occurred: The flow failed to access the value for myVariable_current.Parent.ShippingCity because it hasn't been set or assigned.

Any help is appreciated
 

I am beginner :  Not able to solve Trailhead challange for-Developer Beginner :Process Automation-Automate Basic Business Processes with Process Builder
"
Create a process to update child record when the parent is updated.
You've been given a requirement to keep Contact addresses in sync with the Account they belong to. Use Process Builder to create a new process that updates all child Contact addresses when the address of the Account record is updated. This process:
Can have any name.
Must be activated.
Must update Contact mailing address fields (Street, City, State, Post Code, Country) when the parent Account shipping address field values are updated.
NOTE: You may have to deactivate the validation rule for the Contacts object (created from a previous challenge) in order to complete this challenge."

 What I had tried 
Deleted validation rule on contact  from previous challange.
 Using Process builder created new Process with below details
Object: Account
Criteria:'Update Address' with condidtion

Field: selected shipping street, city, state,postalcode and country
Operator: Ischanged
Type: boolean
value: true

Condition:
Any condition met (OR)

 For Immediate action
Action name: Mailing address change
Records: Account.contacts
Criteria for Updating Records:No criteria—just update the records!

Set new field values for the records you update:

Field: selected Mailing street, city, state,postalcode and country
Type: Reference
value:  selected shipping street, city, state,postalcode and country

 after this saved and activated. So Once I check challange got below error:
"Challenge Not yet complete... here's what's wrong:
An update to an account record failed to update the mailing address fields of all child contact records. Make sure that the process is correct and that it is activated."

So Please help.