Whether you're importing or editing fields on a Stakeholder or Interaction record, there are varying character limits in place for each field.
Stakeholder Record:
Linked Organisation (Individual) / Organisation Name (Organisation) / Linked Stakeholder - 100 characters
Notes/About - 1,000 characters
Contact Groups - 500 characters per Contact Group
Website URL - 500 characters
Customer ID - 500 characters
Everything else - 50 characters
Interaction Record:
Notes/About - 1,000 characters
Contact Groups - 500 characters per Contact Group
Stakeholder First/Last Name/Email - 150 characters
Everything else - 50 characters