How do I bypass the to expensive error in the minecraft anvil?

Unfortunately, there is no way to bypass the "Too Expensive!" warning without mods such as Anvil Fix, unless you are in Creative mode. This applies to all editions of Minecraft.

There may not be a way to bypass the "Too Expensive!" warning, but you can work around it by anviling with a cheaper method. Using this method, it is theoretically possible to apply up to 30 enchantments to something.

The method works like this: Lets say you have a Sharpness V, Looting III, Sweeping Edge III, Mending, Unbreaking III, and Knockback II book.

Let's call these books with only 1 enchantment Book1. Next, combine a Book1 with another Book1 to get a Book2. Book2 should have 2 enchants on them. Repeat these steps:

Book1 + Book1 = Book2

Book2 + Book2 = Book3

Book3 + Book3 = Book4

etc

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If this is unclear, this video does a great job explaining.

The "Too Expensive" warning cannot be bypassed but it doesn't actually cost infinite levels, just a relatively high amount being over 50 or around there. If you are willing to grind some levels using a mob farm or something you can still get all the enchantments on your sword. otherwise you can use the method that @ginkgo suggested.

If you drop your item on the ground and run the command: /data merge entity @e[type=item,distance=..3,limit=1,sort=nearest] {Item:{tag:{RepairCost:0}}}, when you pick up the item, it should have the repair cost reset.