Thousands of music lovers heading to the three-day Sundown Festival in Norwich will have to navigate rail strikes and engineering works.
Sundown, a bass, hip-hop and pop festival, has been held at the Norfolk Showground since 2012.
Chase & Status, Raye and Mae Muller are among this year's headliners.
Rail firm Greater Anglia warned festival-goers that industrial action on Friday and Saturday was set to severely disrupt services.
The action by the RMT union and ASLEF is over a long-running dispute about pay and conditions.
Engineering works are also planned for Saturday.
James Steward, of Greater Anglia, said: "We always want to support local events where possible.
"However, due to industrial action and engineering works over this weekend, we are advising customers to please plan ahead and consider alternative travel arrangements.
"A limited rail replacement service will run, and passengers are advised to check before they travel and allow more time for their journey.
"These buses will be extremely busy, and we are advising anyone attending Sundown festival to consider alternative travel arrangements."
The festival, which runs from Friday to Sunday, has been approached for comment. Its website has recommended campers arrive on the Friday and leave on the Monday.
Norfolk Police said it would be patrolling the event to "ensure festival-goers enjoy the event, as they have previously.
A spokesman said drug use would not be tolerated and searches would be carried out.
The force also urged people to look after one another.
A traffic management system would also be in place around the festival site, police said.