SharePoint : How to make a field mandatory based on another field, in a datasheet list view?

You can use List Settings -> Validation Settings for this.

e.g. =IF([Replacement Available]="Yes",IF([Replacement]="",FALSE,TRUE,TRUE)

This formula would affect the default 'new item' form as well.

[Solved] SharePoint : The selected user(s) may not be valid on the site this workflow is published on.

Sending emails to external users:

If an email address is skipped by the SharePoint 2013 workflow then, instead of adding the email address directly into the TO/CC list add it using a workflow variable.

Create a workflow variable of type string. Assign the email address as value to this variable. And use this variable in the workflow Email.

Make this variable to return Login Name instead of string.

Also, to send emails to external users use the 2010 template of workflow instead of the 2013.

2013 workflows skips the external users while sending mailers.

SharePoint : How to use [Today] in a calculated field?

Option 1: Create a field named 'Today'. Use it in the formula. Now, delete the 'Today' field.

Option 2 (recommended): If possible, use list views instead. You can use [Today] under filter options.

Here you can compare a date field with [Today]+/-SomeNumber.

Example: Date Field1 < [Today]+100

[Solved] SharePoint : No item exist at URL. It may have been deleted or renamed by another user.

Check whether the user has required permission on the list/item or not?

SharePoint List View: How to restrict access to a list view?

1. Edit the page.
2. Edit list view web-part.
3. Advanced > Target Audiences - Specify the SharePoint group here.

Done!

How to trigger SharePoint workflow mailers only on weekdays?

Add a delay before triggering mailer like below:

InfoPath Form: How to fetch current user email?

Current Logged in User

SharePoint On-premise: substring-after(userName(), "\")

SharePoint Online: substring-after(substring-after(userName(), "|"), "|")


From People Picker Field

SharePoint On-premise: concat(substring-after(AccountId, "\"), "@company.com")

SharePoint Online: substring-after(substring-after(AccountId, "|"), "|")