I am trying to re-run a couple of new comparisons using DESeq2. I have previously used this script but something must have changed or updated in the last couple months that is responsible for this. I am trying to perform differential gene expression analysis between and across locations and temperatures. I am intially looking at one temperature condition across 5 locations. I have tried looking at multiple temperatures and location comparisons and have run into the same Warning message.

My data was input as a txt file and the rows and columns were assigned.

#-------- Load data -----------
countData = read.table("allcounts_20.txt",header=TRUE) 
#allcounts_20.txt is subsection of total data
head(countData) 

#--------Make conditions table--------
location=c("MA", "NC", "MA", "NC", "ME", "SC", "ME", "SC", "NS", "NS")
temp = c("20", "20", "20", "20", "20", "20", "20", "20", "20", "20")
individuals = c("A", "B", "C", "D", "A", "B", "C", "D", "A", "B")
#technical replicates

coldata=as.data.frame(cbind(location, temp, individuals))
row.names(coldata) = names(countData)
coldata

# ----------Construct data object ----------------------------------------
dds <- DESeqDataSetFromMatrix(
  countData = countData,
  colData = coldata,
  design = ~ location)

I want to eventually add elements to design, but for now am only looking at a single variable, location. All tables and data look good, but return the following error message:

Warning message:
In DESeqDataSet(se, design = design, ignoreRank) :
  some variables in design formula are characters, converting to factors

I have tried what was suggested previously, but was unsuccessfully.

Any help or suggestions is appreaciated.

This is a warning, not an error. In R, a warning means you can continue (the function will run) but it's telling you something that has happened.

Here it is saying that some variable(s) in the design formula were characters, and that they have been converted to factors.