I am attempting to merge two shapefiles together. Both are line features. I have merged these files before and it worked successfully however due to problems during editing I have to start again and merge the two files once again. However any time I try to merge this time it comes up as a fail and with the results as shown below.
It seems that the shapefiles are locked.
In ArcGis 10.x if a shapefile is opened (in ArcMap or ArcCatalog..), ArcGis automatically creates a file with the same name and pcname.numbers.sr.lock This prevent data as shapefiles to be edited if opened in multiple mxds or ArcCatalog in example.
Try to open a new and empty mxd then run the merge between the two, or just remove the files from the mxd you are using, save, and run the merge again. If it fails again, manually delete the .lock files from the folder.
Beware that ArcCatalog is closed during the merge, sometimes it can cause the lock.