The file path .../versions.tf already exists and was not generated by terragrunt

TL;DR: Your generate block targets versions.tf, but the module you're consuming ships its own versions.tf, and overwrite_terragrunt refuses to clobber a file it didn't write. Don't switch to overwrite (it silently deletes the module's constraints); scope the generate block so it doesn't fire for modules that bring their own, or drop the generate in favor of the module's file.

ERROR: The file path .../versions.tf already exists and was not generated by terragrunt.

Steps

1. Confirm the collision: the error names the path; check the module source for a versions.tf it ships.

Expected: the module (e.g. a terraform-aws-modules package) contains its own versions.tf.

1. Pick one:

• If the module's pins are acceptable: stop generating versions.tf for that unit (condition the generate block or move it out of the shared config).
• If you must enforce your pins: generate to a differently-named file is NOT enough (only one required_providers per module); instead constrain via the module call or a version constraint the module honors.

Expected: exactly one source of required_providers per unit.

1. Re-run.

Expected: the error is gone and tofu init/terraform init resolves providers.

When this applies

• A generate block with if_exists = "overwrite_terragrunt" (or error) targets a filename the module also ships.
• Common with versions.tf, provider.tf, backend.tf injected from a root config.

When it doesn't apply

• You WROTE the existing file by hand and want Terragrunt's version: that's what overwrite_terragrunt is for; check the file's signature comment to see why Terragrunt doesn't recognize it (e.g. disable_signature = true was used).

Tool versions

All Terragrunt 1.x.

Why it happens

overwrite_terragrunt replaces a file only if Terragrunt generated it (recognized by its signature comment). A module's own versions.tf was written by a human upstream, so Terragrunt stops rather than silently deleting someone else's version pins.

Edge cases

• if_exists = "skip" makes the error go away but silently disables your pin wherever the module ships the file; the inconsistency is invisible.
• if_exists = "overwrite" deletes the module's constraints entirely, and you must then redeclare every provider the module needs and track module updates yourself.