How to fix error: patch failed: file.txt:10 error: file.txt: patch does not apply in Git

# If this succeeds, the patch is already applied
git apply --reverse --check my-patch.patch

# If the regular check fails but reverse check succeeds:
git apply --check my-patch.patch      # This will fail
git apply --reverse --check my-patch.patch  # This will succeed

git apply -v my-patch.patch

Checking patch file.txt...
error: while searching for:
    expected context line 1
    expected context line 2
error: patch failed: file.txt:10

git apply --3way my-patch.patch

git apply --reject my-patch.patch

# Check for rejection files
find . -name "*.rej"

# Review a rejection file
cat file.txt.rej

# Ignore whitespace when matching context
git apply --ignore-whitespace my-patch.patch

# Also ignore changes in whitespace amount
git apply --ignore-space-change my-patch.patch

# Fix whitespace issues according to core.whitespace
git apply --whitespace=fix my-patch.patch

# Convert patch line endings to Unix format
sed -i 's/\r$//' my-patch.patch

# Check the paths in the patch file
head -20 my-patch.patch

# You might see paths like:
# --- a/src/file.txt
# +++ b/src/file.txt

# Make sure you're at the repository root
cd $(git rev-parse --show-toplevel)
git apply my-patch.patch

# Strip 1 leading path component (removes a/ and b/)
git apply -p1 my-patch.patch

# Strip 2 leading components
git apply -p2 my-patch.patch

# Generate patch with 10 lines of context instead of default 3
git diff -U10 commit1 commit2 > patch-with-context.patch

# Or generate with maximum context
git diff -U999 commit1 commit2 > full-context.patch

# Apply the new patch
git apply patch-with-context.patch

# Apply email-formatted patch
git am my-patch.patch

# If it fails, you can skip or abort
git am --skip    # Skip this patch and continue with next
git am --abort   # Abort the entire operation

# Use 3-way merge with git am
git am --3way my-patch.patch